[ipsi]

It depends what you do - I've always had to timesheet, but that's because I was working for clients, so we had to at the very least make sure we were estimating correctly, or, at my current job, that we're billing the hours I actually work.

It's not too onerous, since I only work for one client at a time, and time spent not at work is uncommon and usually in big chunks (e.g. an hour or two for a doctor's visit, days or weeks for vacation).