You can request tickets as often as you like; however, the more you request, the less likely you are to receive tickets.
For example, if you are trying to go to a Bucks game, and to improve your chances, you request tickets for all home games for the next two months. Even if you’re only trying to go to one, those other requests will be taken into account by both your manager and by Marty and likely lead to all requests being denied.
It is highly recommended that you be selective with your requests.