I don't recommend it because it's a pain in the ass that leads to more work for the mods and unnecessary competitive melodrama. Nobody can bitch about the mods being biased if it's first come first served. People also tend to get over it if they lost out on a reserve because they were too slow to submit theirs a lot faster than getting their apps declined because they were competing with someone else for the slot, especially if there is an insular cast/clique involved. If you're worried about quality then make your baseline app standards higher.

You can always just switch out what time reserves open from month to month to make it more fair to people in different timezones.