How long do you aim to retain focus for your deep work?

I aim for three 45 minutes
between each 5 minutes break.
Actually every 20 minutes I need to take a small break while I am sitting.

I aim to retain focus during my deep work for no less than 10 minutes. This allows me to tap into my creative mind while testing or troubleshooting a problem so that I come up with the best execution or action plan.

I use the Pomodoro (tomato timer) method of 25 minutes of focus then 5 minutes of break. I can push myself to stay focused on almost anything for 25 minutes, and can put off distractions knowing that I have a 5-minute break coming up to check email, make tea, or just stretch.

Long enough that I don’t feel I’ve cheated myself. I don’t have to have been productive in any visible sense; just know I’ve tried my best