I have to keep detailed hours on a daily basis for work. No interest in doing so for my hobby. But yes being self employed I am a bit obsessed over time and how it relates to the all mighty dollar. I have thought about tracking time and expense in the past but in the long run just decided against it. After having tracked my time for the last 20 years I have a good sense of how long I spend on tasks. I can look back and do a pretty good estimate of the time I have into something. I keep receipts but do not want to add them up
If you really want to know you can get a time clock at staples for not much money. Just use the punch in and out card everytime you go to the shop.