Does it matter how long people work in any day or week?

Ten people can do the same work at ten different rates and even then, the doneness of their work can vary in terms of value delivered. One person can deliver more value in an hour than someone else does in two or six hours. 

So, it doesn't matter how long people work if we care about how much people deliver. It's a case for measuring workloads in terms of value delivered rather than the duration of effort invested.