I work both Sat and Sun. we are required to work both every weekend. The managers do get Sundays off now n then. But they are pretty good if you need a Sunday off, you just request it before the schedule is made same goes for Sat. but Sat's are mandatory. DON'T ever call out unless it's a true emergency or your really sick as they may ask for a doctors note. Plus it makes it hard on your co-workers, I had to come in 2 hrs earlier on a Sunday due to one of our girls calling out. But hey, it happens and if your flexible - then they will remember that when you request a day off!
Hope this helped.