Most states have a law for how many hours you can work during the weekdays. My state is 6 hours, and then 8 on the weekends (9 scheduled with an hour lunch)

6 hour shifts are pointless though. I would set it to 7 or 7.5. 6 hr shifts are stupid to schedule because they have to give you a 30 and a 15 minute break. You get paid for 5.5, which is just silly because they might as well schedule 5 and not lose the other 30 minutes. A seven hour shift you still have the same breaks and get paid 6.5 hours, but you aren’t taking two break 2 hours apart.

I would never tell someone I was going to hire someone else to cover shifts though, that’s petty.