That wouldn't work with ADHD. You'd probably sit down and think about all the things you could do with that time without actually doing them while continuously

That wouldn't work with ADHD. You'd probably sit down and think about all the things you could do with that time without actually doing them while continuously scolding yourself for not doing them, and then get up 5 hours later, 3 of which you felt hungry and 2 of which you felt like going to the toilet.