Tap, jazz and ballet are very fun! I do them all, have been for years and love them. :)
I am concerned however.... you said they're combinations. Do you mean that they're one hour classes back to back with one another that you switch to each one, (which is done a lot, i've done it myself) or is it like a full 1 hour class with tap, jazz, AND ballet crammed into it?
If it's running from one class to the next right after the other ends, i've done it before multiple times, running from one teacher to the next. That's fine, nothing to worry about.
When I hear "Combination classes" however, it makes me think of what they have for the little kids with a half hour of one style in it with a half hour of another. Sometimes, it's even more! With classes like that you don't learn anything, and if they have those for like teenagers and such, I'd run since that sounds very much like a Dolly Dinkle school. Not safe and you learn nothing.
Hope I helped.
Ballet dancer for 12 years, tap and jazz dancer for 7 years.