Wow. I can't believe that anyone would ask to be interrupted every f'ing ten minutes for nothing.
I can't stand being interrupted more than once or twice a day.
I wrote and ran something like this but the sweet spot was 20 min not 10. The purpose for me was to discover how many 20 min chunks of time were actually productive. The efficiency of planned tasks declines when you assign more hours to it.
But that was not what I ended up measuring. The widget (it was) was like someone looking over my shoulder and modified my behavior. I became insanely productive for a few days then had a weird kind off burn out where I declined to enter anything or wrote "watching youtube videos" for days.
Eventually I replaced the widget with a careful cut out from the movie 1984 so that it looked like a telescreen with big brother looking at me. A factory bell would ring and I would be "forced" to take a break. I got bored with that before figuring out the ideal work/break ratio. (It didnt care what I was doing)
I considered automating self-inflicted activity monitoring but any amount alters your behavior... much like your gut told you it would.
As well as a reminder for those not good at staying on task, it sounds worth considering for those who spend their day satisfying constant small ad hoc requests who later get asked "What have you been doing all day?"
Hopefully it has a "same as last time" button, I doubt this has the same cognitive distraction level as fielding a question from a colleague as well. I.e. understand their question, think of the context, etc etc
The person you're referring to is talking about a different kind of focus -- focus as in not going off task.
Some of us have a habit of getting distracted from the task at hand easily and going off on a HN/Youtube/Reddit/browsing/timewasting session.
Continual prompts like this you could catch this within 10 minutes in to a timewasting session and remind you to get back to work.
Personally I probably wouldn't use 10 minutes though as it seems a little too frequent and would go closer to the standard Pomodoro time of 25 minutes (which I have personally used and found useful).
