Do you record when employees come and leave? we currently don't and it's pretty flexible and that's one of the questions that I don't have an answer for. Should it kept flexible and team can come and leave when they need to or set some rules to manage that.
When you have 1000 employees, you can't keep track anymore. Some large companies have computer systems that register total monthly time using chip cards.
I don't manage employees myself, just my experience.