A shorter start, or a longer stretch?
25/5 and 50/10 are two example rhythms to try. Neither is a rule for how your attention should work.
25 minutes of focus, 5 minutes of break.
A shorter block may be a useful starting point when you are hesitating, switching tasks or working through a small unit. Set the timer and see whether that boundary suits today’s work.
Draft an opening paragraph or work through a few practice problems.
50 minutes of focus, 10 minutes of break.
A longer block may fit work that takes time to get into. It is an option, not an achievement to unlock. If it makes beginning harder, use a shorter session.
Before choosing 50/10, name the work you will carry through both halves of the block. If you keep switching tabs or running out of a clear next step, try 25/5 next time instead.
Continue an established writing draft or read a longer section with notes.