Wonder how much time it takes for 30 machines to login and authenticate.

Per radio it typically takes 5-10 seconds (min).

Since Wi-Fi is contention based (i.e. each user waits in line for their turn), the time for the last user to log in is up to 300 seconds (5 MINUTES!!!). And, that's just for logins, imagine the length of a group downloading a video!

Stand alone APs are a bad choice but I'd imagine this school didn't test for contention. Most don't.

When reviewing what you choose, look for multiradio array architectures and TEST for contention based affects.