I think it depends on your area. But for example, during my CP I wasn't on a fixed schedule for the first part, but then I was switched to a 4 day-10 hour work week so I went in at 11, stayed until 9ish; but my days off varied. When I switched over to MK as a Part-time my hours changed but my days off didnt, but that's because of my avaliblility. Full timers in both areas usually had the same days off but some of them had different hours. I worked in Outdoor Foods though, so the hours of operation was never set in stone.
Basically, CP, no set schedule, PT, sometimes set schedule, FT, mostly set schedule.