it depends on
1. the job scope
2. the unit requirement
for example, staff officers work 8 to 5 - working you see. however,
if you are with a combat unit which is currently in training phase,
there may be a requirement for you to stay in, especially if you
are doing your PC tour.
you seemed very concerned about this booking out thing. if you
intend to sign on, you must understand that you have to go by the
requirements of the work, and this may mean staying in (whether its
for an extended period or from time to time). however if you are
just going to serve your ns, you can go by the "worst case"
assumption (which is usually correct, since a NSF can only be
deployed to that many vocations) that you need to stay in. and of
course, book out during weekends.