For the last 15 years or so:
1500-2300
1300-2100
0800-1600
0600-1400...2230-0630
2 days off
or
1500-2300
1300-2100
1000-1800
0800-1600
0600-1400
2 days off
Some small variations to the above, but that's the basic watch schedule for a lot of U.S. Tower/Tracons. We bid our days off once each year.