Drafting is the deepest kind of focus there is. You are holding a sentence, the one after it, and the shape of the whole paragraph in your head at once. A single check of the phone does not cost you thirty seconds. It costs you the fragile stack you spent ten minutes building, and you have to rebuild it from the bottom. The interruption is cheap. The recovery is not.
Telling yourself you will just leave the phone across the room does not survive the first hard sentence. Reminder apps do not either, because the override is one tap and the override costs nothing, so it becomes part of the loop. The mechanism has to refuse the cheap override. You set a daily limit and the apps it covers, and when you cross it those apps lock at the operating-system level, not behind a popup you swipe away.
You earn them back with something real: 25 camera-counted pushups, 25 squats, 1,000 verified steps, or 10 mindful minutes. Going over never costs money. The only thing you pay is the flat dollar a week, and the overage is settled in effort, not dollars.