In order to get randomized alarms for your time logging, I can recommend you an app for the iPhone.
It is called: Mind Jogger
You can define up to 64 (randomized) alarms per day on it.
Unfortunately it is not free, while it was definitely worthy to invest a very little instead of programming my timer / alarms for 50 "rings" per day.
Since I am doing this logging, I am working more focussed than before - at least I get this feeling.
Thanks for the cast.
(a high D)