My team do 37.5 hrs per week, with a range of starting & finishing times, at times a couple of them work 4 days instead of 5 and one does about 2 out of three Saturday mornings.
I hope that they can be flexible and not clock watch when a project demands that little bit extra - and I'll reciprocate with TOIL or an alternative reward.
However, I don't tolerate deliberate time-wasting, there's always a bit of cleaning or something that can be done at the end of the day. They do get a reasonable few minutes to pack up and wash hands etc ...
Personally, I work all sorts of odd hours - many of our clients have meetings etc out of normal business hours so I need to be fairly flexible.
In recent months I've done most of my admin WFH - although I do have facilities in my office there, it is difficult to concentrate with wood-working machines active in the same building !