In our area, Friday meets do happen, but are rare. However, they are scheduled late enough that most kids should not have to leave school early, though it might be a time crunch to get hair ready etc.
In some areas, however, I have heard that Friday meets are more normal. In Utah, for example, they don't usually compete on Sundays, so Friday meets are more common.
Also, larger meets will often need 3 days to complete all the sessions needed for all the competitors.
The best thing, would just be to ask the gym if this is normal. Also find out their policies. If you don't want to pull your child out of school for a meet, is it ok with them if she misses these. Every gym has a different policy & philosophy on these things, so it's best to find out before you commit.