How long a focus session should actually be

The Pomodoro Technique gave a lot of people their first taste of focused work, and that is genuinely valuable. Twenty-five minutes is short enough to start when starting is the hard part. But somewhere along the way, 25 minutes stopped being a starting line and became a target. That part the research does not support.

What elite performers actually do

The most cited work on deliberate practice, by Anders Ericsson and colleagues, studied how top performers train. The pattern was consistent: they worked in focused bouts of roughly 60 to 90 minutes, took real breaks between them, and rarely exceeded about four hours of true deliberate practice in a day. Past that, performance and error rates degraded regardless of motivation. The limit was physiological, not a question of grit (overview).

This lines up with the body’s basic rest-activity cycle, an ultradian rhythm of about 90 minutes, where the first 60 to 70 minutes run at higher alertness and the last stretch tapers. Individual cycles vary, roughly 75 to 120 minutes, so the exact number is personal.

The number is softer than people pretend

Worth saying plainly: the precise “90 minutes” is not sacred. A 2025 analysis of DeskTime data found that the most productive workers averaged about 75 minutes of focused work followed by 33 minutes of rest (writeup). That is shorter than the classic 90, but in the same neighborhood, and the direction is what matters.

The direction is this: real progress wants blocks measured in the better part of an hour, not in 25-minute sprints. A short block is great for breaking the inertia of starting. It is not where deep work happens.

The two things to get right

1. Long enough to get in. If it takes 20 minutes to fully re-immerse in a task, a 25-minute block gives you about 5 good minutes before the timer pulls you out. Aim for blocks where the warm-up is a small fraction of the total.
2. A real stop. The four-hour ceiling is real. Beyond it, you are not adding output, you are adding errors. Breaks are not a reward for working, they are part of how the work stays good.

How 6s handles session length

We tried to take the useful part of Pomodoro (a clear, low-friction way to start) without inheriting the wrong target.

• Start small, run long. The focus clock opens with a Pomodoro-style ring so starting feels easy, but it keeps counting. You are not yanked out at 25 minutes. You ride the session as long as the work is flowing.
• A session cap that matches the biology. A single session credits up to 90 minutes. That is not a punishment, it is the gentle “time for a break” the research points to, placed exactly where focus reliably starts to fade.
• A daily ceiling. There is a cap on how much focused time earns credit in a day, because the science is clear that hour five of “focus” is mostly fumes. The product will not reward you for grinding past the point of useful work.
• Only real time counts. If you go idle mid-session, the clock pauses and credits only up to your last real activity. Time on task means attention on task, not a timer left running while you make coffee.

Use a short block to beat the friction of starting. Then let it run toward the hour. That is where the work that moves the needle actually gets done.