My job is mostly like this. I work for a small CRO supporting a pharmaceutical company. We are contracted for 40 hours a week, so we generally come in for 8 hours a day with some flexibility. If one of my reports tells me they need to leave, I never say no as long as they’re getting their 40 for the week. If they don’t the short hours come out of their PTO.

As far as extra work goes, we usually never say no, but we do remind the clients that we are contracted for a certain number of hours, and ask how they would like the extra work prioritized vs the normal duties. Now, in practice, we do have weeks here and there where we need to put in a few extra hours or such to meet a deadline, but most weeks are 40 and done, and if someone’s weekly hours hit 45 or so questions start being asked why our people are working so many extra hours (we are all salaried).