This all depends on location. My location was open 8am-8pm. It was dead after 7:30pm. Days prior to Halloween are the days the stores typically stay open late
You give them the days/hours you are available and they make a schedule from there. I worked pretty close to the schedule I gave them, and sometimes I worked overtime if they needed me to stay or I came in when they needed someone to fill in for someone who couldn't make their shift.
5-8 hours a day.