I'm pretty junior, so I'm pulling reserve with a US major. 19 days of work, 12 off. There are various lines to bid including some with the 12 days split into two duty-free-periods (DFPs), some split into 3 DFPs. I bid the 2 DFP reserve lines becuase I commute to work and it cuts down my lost duty free time commuting. Regular line holders (vs. reserve) work anywhere from 9 days a month (very senior) all the way up to 17-19.
TWA had/has a "preferential" bid system, where you put into the computer the days and places you wanted to fly and it would crunch out schedules. Most TWA guys I've talked to liked the system.
If you don't have at least some sort of sched bidding system at your airline, you're probably being screwed.