The contract at my company requires the following:
10 minimum days off
no less than 2 days off at a time
no more than 5 days on at a time
no more than 4 days to a single trip
So, what this equates to is a schedule like this (for reserve purposes)
5 days of reserve, followed by 2 days off, followed by 5 days of reserve, followed by 3 days off, followed by 5 days of reserve, followed by 2 days off... you get the idea. 2 3-day weekends and 2 2-day weekends. The weekend days may be any day of the week, and that is where bidding comes in. Senior people get saturday and sunday off, if that is what they want. Commuters often prefer conventional weekdays off since travelling can be easier on those days.
Since a bid period is 30 days, that makes 10 days off and 20 days of reserve, split into 4 blocks of 5 days each.
Our lines typically have between 10-14 days off, with trips of up to 4 days. Sometimes there are more out-and-backs, sometimes there are CDOs or highspeeds (this is where you work the last flight in to an outstation, sleep about 4 hours, then take out the originating morning flight). The beauty of the bidding system is that the company (ideally, at least) publishes several different types of schedules. For instance, some people like to have 4 day trips all the time. Some prefer to be home every day with out-and-backs. Because of the per diem calculations, being out overnight is worth about $13-$20 more on average per night. For some people that isn't worth it. For the ones who live in crashpads or pay by the night in hotels, you can imagine that they are all for it.