The 90-Minute Technique for Deep Work Across Multiple Projects: A Practical Guide

Juggling multiple projects or jobs is a common challenge for freelancers, entrepreneurs, and professionals who wear many hats. The 90-minute technique for deep work across multiple projects is rooted in the science of ultradian rhythms—natural 90-120 minute cycles during which our brains alternate between high and low cognitive activity. Leveraging these blocks not only enhances the quality of your output but also reduces mental fatigue and improves your ability to switch between complex tasks without losing depth. In this guide, we’ll explore how to implement this technique realistically, with concrete examples and strategies to adapt it to environments with competing demands.

Why 90 Minutes? The Science Behind Deep Work Blocks

The human body operates in approximately 90-minute cycles known as ultradian rhythms. During these periods, we transition from a state of high energy and focus to one of fatigue and the need for rest. Research in chronobiology suggests that working in sync with these cycles—rather than forcing ourselves to maintain attention for hours—optimizes productivity and creativity. A 90-minute deep work block allows you to immerse yourself in a complex task without interruptions, while extending it beyond 120 minutes often leads to diminishing returns: errors, distractions, and reduced information retention.

For those managing multiple projects or jobs, this technique is particularly valuable. Instead of jumping between tasks every 20-30 minutes (as the Pomodoro method suggests), 90-minute blocks let you make meaningful progress on a single project before switching contexts. This reduces the cognitive load associated with multitasking and improves the quality of the work delivered. For example, a designer juggling three clients can dedicate a block to each one, ensuring every project receives undivided attention rather than fragmented progress.

How to Structure Your 90-Minute Blocks for Multiple Projects

1. Prioritize and Assign Blocks by Project

The first step is identifying which projects require deep work and which can be handled with shallow tasks. Use a prioritization matrix (like the Eisenhower Matrix) to classify your projects based on urgency and importance. Then, assign 90-minute blocks to the projects that demand the most focus. For example:

• Project A (urgent and important): 2 blocks of 90 minutes per day (morning and afternoon).
• Project B (important but not urgent): 1 block daily, preferably during your peak energy hours.
• Project C (urgent but not important): Short tasks between blocks or at the end of the day.
• Administrative tasks: Grouped into a 30-45 minute block, without encroaching on deep work time.

This distribution prevents lower-priority projects from draining your mental energy. If a task doesn’t deserve a 90-minute block, it can likely be resolved in less time or delegated.

2. Prepare Your Environment to Minimize Distractions

A 90-minute deep work block requires an interruption-free environment. Before starting:

• Silence notifications: Turn off email, social media, and messaging app alerts. Use "Do Not Disturb" mode on your devices or tools like Freedom or Cold Turkey to block distracting websites.
• Communicate your availability: If you work in a team, let others know you’ll be in deep work mode and define an emergency channel (e.g., Slack messages with a #urgent tag).
• Prepare materials: Have everything you need for the project (documents, tools, references) at hand to avoid breaking your flow to search for something.
• Choose the right space: If working from home, use a dedicated room or corner. In an office, consider noise-canceling headphones with white noise or instrumental music to isolate yourself.

A useful trick is to create a starting ritual: for example, having a coffee, opening only the necessary tabs, and writing down the block’s goal on paper. This signals to your brain that it’s time to focus.

3. Divide the Block into Phases to Maintain Energy

While the block is 90 minutes long, you can structure it internally to avoid fatigue:

• 0-10 minutes: Quick review of the goal and planning. Write down what you want to achieve in this block (e.g., "Finish the draft report for client X").
• 10-70 minutes: Deep work without interruptions. Focus on the most complex or creative task of the project.
• 70-80 minutes: Review and adjust. Check if you’re on track or need to make corrections before finishing.
• 80-90 minutes: Wrap-up and transition. Note what you accomplished and what’s left for the next block. This makes it easier to pick up the project later.

If you notice your concentration waning before 90 minutes, try shorter blocks (60 minutes) and gradually increase the duration. The key is not to force the time but to adapt it to your natural rhythm.

How to Switch Between Multiple Projects Without Losing Focus

One of the biggest challenges of the 90-minute technique for deep work across multiple projects is context-switching without losing efficiency. Every time you move from one project to another, your brain needs time to "load" the relevant information. To minimize this cost, follow these strategies:

1. Group Similar Tasks

If two projects require similar skills (e.g., writing reports for two different clients), schedule their 90-minute blocks back-to-back. This reduces cognitive friction when switching tasks. For example:

• Block 1 (9:00-10:30): Writing a report for client A (creative work).
• Block 2 (10:45-12:15): Writing a proposal for client B (same type of task).
• Block 3 (1:00-2:30): Data analysis for client C (analytical task, different from the previous ones).

2. Use Active Transitions

Between blocks, take an active transition to reset your mind. Some options:

• Physical movement: Walk for 5-10 minutes, stretch, or do breathing exercises. This oxygenates your brain and reduces stress.
• Change your environment: If working from home, step outside or move to a different room. In an office, visit the kitchen or a common area.
• Mechanical task: Tidy your desk, file documents, or make a short unrelated call. This gives your mind a break without disrupting your flow.

3. Document the Status of Each Project

At the end of a block, jot down in a visible place (a notebook, an app, or a document) what you accomplished and what’s left to do. Include details like:

• The specific goal you met (e.g., "Finished section 2 of the report").
• The next step (e.g., "Review data in section 3 with the client").
• Any ideas or roadblocks that came up (e.g., "Pending confirmation of delivery date with the team").

This allows you to pick up the project in the next block without wasting time remembering where you left off. If using digital tools, tag each note with the project name for quick retrieval.

Practical Example: A Day with 90-Minute Blocks for Three Projects

Imagine you’re a freelance developer with three active projects: an app for client A, a website for client B, and your own online course. Here’s how you could structure your day using the 90-minute technique for deep work across multiple projects:

• 7:30-9:00 AM: Block 1 - App development (client A). Task: Implement payment functionality. Result: Code ready for review.
• 9:00-9:30 AM: Active transition (breakfast + urgent email check).
• 9:30-11:00 AM: Block 2 - Online course (personal project). Task: Record lesson 3. Result: Video edited and uploaded to the platform.
• 11:00-11:30 AM: Active transition (short walk + call with client B to confirm requirements).
• 11:30 AM-1:00 PM: Block 3 - Website (client B). Task: Design the homepage. Result: Mockup approved by the client.
• 1:00-2:30 PM: Lunch and screen-free break.
• 2:30-4:00 PM: Block 4 - App (client A). Task: Fix reported bugs. Result: List of resolved errors.
• 4:00-4:30 PM: Active transition (snack + review of pending tasks).
• 4:30-6:00 PM: Block 5 - Online course. Task: Write script for lesson 4. Result: Script completed and sent for review.

In this example, each project receives deep attention without overlap, and active transitions prevent fatigue. Additionally, grouping similar tasks (e.g., app development in two consecutive blocks) reduces the cost of context-switching.

Common Mistakes and How to Avoid Them

Implementing the 90-minute technique for deep work isn’t foolproof. Here are the most common mistakes and how to fix them:

1. Underestimating Preparation Time

Many start a block without a clear plan, wasting the first 10-15 minutes deciding what to do. Solution: Before starting, define the block’s goal in one sentence (e.g., "Finish the logo design for client X"). If you can’t summarize it, the task is likely too vague.

2. Skipping Breaks

Skipping active transitions or working for more than 120 minutes straight leads to accumulated fatigue. Solution: Use alarms to mark the start and end of each block. If a project absorbs you, set a visual reminder (e.g., a sticky note on your screen) to stop at 90 minutes.

3. Multitasking Within the Block

Trying to make progress on two projects simultaneously during a 90-minute block dilutes your focus. Solution: If an urgent task from another project arises, jot it down on a "pending" list and return to it in its assigned block. Use the two-minute rule: if the interruption takes less than two minutes, handle it; if not, postpone it.

4. Ignoring Fatigue Signals

Forcing concentration when your brain is exhausted (e.g., after lunch or at the end of the day) reduces work quality. Solution: Schedule the most demanding blocks during your peak energy hours (for most people, in the morning). Use afternoon blocks for less demanding or administrative tasks.

Productivity isn’t measured by hours worked, but by the depth and quality of output during moments of full concentration.

Tools to Apply the 90-Minute Technique (and How Foco Can Help)

Implementing deep work blocks requires organization, especially when managing multiple projects or jobs. Here are some useful tools:

• Calendars: Google Calendar or Outlook to block 90-minute slots and avoid scheduling meetings during those times. Use different colors for each project.
• Timers: Apps like Toggl Track or Forest to measure focus time and avoid distractions.
• Task managers: Tools like Todoist or Asana to organize tasks for each project and prioritize them based on assigned blocks.
• Distraction blockers: Freedom or Cold Turkey to disable social media and unrelated websites during blocks.

If you’re looking for a solution that integrates several of these functions, Foco can be a practical option. The app lets you create project containers (each with its own color), making it easier to visualize your 90-minute blocks and switch between projects without losing track. For example, you can use the Panorama mode to see all your pending tasks (each with its project’s color) and then enter Focus mode to concentrate on a single project. The List or Kanban views help organize tasks within each block, while the Calendar syncs external events to avoid overlaps. Additionally, the voice capture feature is useful for quickly logging ideas or pending tasks between blocks without breaking your concentration.

The key is to choose tools that adapt to your workflow, not the other way around. The 90-minute technique for deep work across multiple projects works best when your organization system is simple and flexible, allowing you to focus on what matters: deep work.