At the same job? 6 hours. I would work 3:30-12:00 and then 6:00-2:30 the next morning. That was actually against the company policy (they guaranteed at least 8 hours between shifts), but I was going to school full time and working full time. It was my request to work those shifts since it was around my school schedule.
At different jobs, even less. I used to teach in North Carolina. I also worked part time retail. At Christmastime, it was more like full time retail. In December, we had extended hours PLUS we couldn't leave until the store was set for the following day.
In December, my schedule typically looked like:
leave for work @ 6:45 am
Arrive @ work by 7:30 am (had to pass TWO high schools, so traffic was always iffy in the morning.)
Leave work @ 3:45 pm
Arrive home @ 4:10 pm change clothes, grab something to eat,
Leave for work @ 4:30 pm (driving 20-30 minutes in the OTHER direction- it is about 10 minutes during other months, but it was a major shopping area, so traffic was terrible in December)
Arrive at work @ 5:00 pm
Store closes at Midnight- leave work anywhere between 1 am and 3 am, depending on how long it takes to set for the morning. Sleep for about two hours. Repeat. The days where I didn't work both places is when I wrote my lesson plans and graded papers. It was so much fun.