Whatever solution you choose, there are two key points: 1) Make it as frictionless as possible for the people tracking their time, or you will inevitably have

Whatever solution you choose, there are two key points: 1) Make it as frictionless as possible for the people tracking their time, or you will inevitably have people not doing it, and then someone has to hound them, and then they just put in junk data just to stop the hounding. Your "to the hour" metrics end up just being junk. 2) If you aren't actually using the data, don't make people track their time "just in case". Or at least assign it a real cost, and say, "Is this data worth 2% of my payroll to me?" In poorly run companies, this tends to be a classic example of management wasting the employees time for no reason, just because someone said they were supposed to do time tracking but management never gets around to using the data for anything.