I can't speak for anyone else, but the job I posted in October for a curatorial
position at the Oregon Historical Society closed Dec. 31 (that's 3 months); it had
a start date (Apr 1) and I posted it and I'm the one reviewing apps.  I know none
of people we're interested in interviewing further.

We use Museum-L for job listings because we think it is one of the easiest ways
to get the widest spectrum of museum professionals (not everyone belongs to
AAM/AASLH).  It is also a lot cheaper than an Aviso ad.  We also advertise in
Aviso, History News, and the local newspaper when time allows.

I suspect that the 2 week deadlines are for positions that are already filled.
That's just a fact of life.  Sometimes someone quits and you have to fill the
position immediately.  If you're not in a hiring position then it's pretty easy to say
that the system is skewed and sometimes it is, but the process is not always as
simple as it might appear.