Thanks this sounds like something I'd like to try - are there any others you considered whilst looking around as that is mac only and I'm Windows unfltunately ( or any one else in this thread do something similar )

Yes I think I remember RescueTime but that doesn't store your data locally I think?

I'm using Timeular which is an octahedron with erasable sides. It tracks whichever side is facing up. You just have to remember to flip it, which is a good way to notice 'hey, should I really be switching tasks'?