I can speak of the Northeast operation only. Usually 2 FO's per outstation. 4 on/4 off rotating schedule. I think the hub bases (BOS) have a 4 on/3 off schedule. I'm captain now so not too sure with the FO world. In the Northeast Region, if you are based in an EAS outstation, they are 13 hour duty days usually, with 6 legs per day, about an hour each. Generally you will fly a lot more as an FO in the winter, since the flight loads are lower. Unfortunately a passenger will end up taking your seat more often in the summer when business picks up. I averaged about 60-70 hours a month as an FO, but YMMV. I get the impression that guys are really getting a lot of flying out in Montana.