Rhino is talking about RMPs, and they're very closely watched nowadays as there was a tendency in some units to abuse them, by both individuals and the command.
There's not really a single answer to "how the reserve works" because every unit does things vastly differently depending on their funding and mission. The ACCLW SAU does mando DWEs 3-4 times a year, but otherwise we're pretty much never together in one place. Since the mission is Fleet/FRS support, we generally don't do much on the weekends, because there's generally not much requirement for support on weekends. On the other hand, I've seen OSUs that only work weekends because their tasking is covering 'outside normal working hours' periods for their AC counterpart (VP flying weekends, for example). I briefly drilled with a Maritime Expeditionary Security unit that had a DWE every month and unless you were dead or in hospital, you were expected to be there. So when you're looking at a Reserve unit, one of the main things they'll look at is how much time you can give them, based on their drill requirements, mission, how far away you live, your civilian work requirements, etc. Another example, there's lots of airline guys at the VRs, not least because they can take a plane to Sigonella for a week at fairly short notice. Hard for a guy who's a manager at GE to do that.
