The way our shop does it is everyone comes in the morning to the meeting room and sits at a table and fills out their workorders and time cards(which show total hours, work order(s) name and number, and obviously name and date) from the day before. About an hour later our office guy grabs all of it and verifies the time cards match the hours on the work orders. If it doesn't, you get a phone call.
Honestly, there's often mistakes with one thing or another so the office guy just fixes it. But if he can't figure out what you were trying to do, then you get the phone call.
Sometimes we'll work on something for the company in the shop or work up bids(we give free estimates) for things like that that don't have a work order(unbillable time), so we'll just write down "shop."