not in a lot of jobs no, leaving it that late could mean too many others have already booked the same date leaving no cover so no day off.
or people have committed themselves to do some thing else
you are assuming people know these events exist, what's wrong with putting all the threads up so people can book time off early and make sure they keep their day free for the show? it shouldn't be too hard its not like the old days when FF did lots of shows its only 3 a year now
the fact a member has asked for the thread shows there is a need