Set your focus, take three breaths, and work ten minutes at a time. A bell keeps the hour so you never watch the clock.
The (10+2)×5 hack comes from Merlin Mann's 43 Folders: ten minutes of work, two of guilt-free break, five times. It is the seed protocol behind High-Intensity Interval Thinking. Every bell is synthesized live, so nothing loads and it works offline.
A timer protects the hour. It cannot tell you whether the hour was pointed at the right thing. That is a different problem, and no timer, app or board has ever solved it.
I give this away because it is a real tool and because it is the smallest honest sample of how I work. The actual work is two and a half hours naming the thing, then twelve weeks finishing it.
If you keep running clean hours at the wrong thing, the fix is upstream. The Implementation Backbone gets every open loop out of your head and onto one board so you can see what you are actually choosing between. Forty five minutes, twenty nine dollars.
And if the board fills up and you still cannot pick, that is not a system problem either. No board can rank your work against a destination you have never named out loud. That is what Moonshot Mapping is for, and there is a free fifteen minutes on that page before you decide anything.