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.
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
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).