Sounds like the Pomodoro Technique [0] (also mentioned in the article). Glad it is working out for you!
I tried that to help with my ADHD with very little and very fleeting success.
The classic Pomodoro is said to be 25minn + 5 mins break, which adds up to half an hour, which is a common measurement unit for time worked. I've discovered that for my needs, a 20 min pomodoro with 5 mins rest works better.
The problem is that Pomodoros are hard to count if you hit flow state and find it hard to stop when the timer rings.
The problem is that Pomodoros are hard to count if you hit flow state and find it hard to stop when the timer rings.