How does a total of 40 hours per week affect the predicability of being there at the same time in a way that 35, 39, or 42 hours maximum per week could not?
9-4 you'll be in the office and ready to pair, and lunch for everyone is 12-1 regardless of when you got there; but you can come in at 7 and leave at 4 if you want, or get in at 9 and stay til 6 or work at home later if that works better.
you need that strictness of "pairing time starts now" otherwise you have people coming and going and needing breaks at all different times and it gets disruptive.
I am afraid I still don't quite see what impact the total maximum hours for a week has to do with predictability of scheduling. What am I missing?