How many times can you “winback” in a 1-2 year period?

Edit: my question isn’t clear it seems. I’m not referring how long you have to be a returning customer. Everyone knows it’s 90 days or you’re a new customer.

Rephrase:

Does T-Mobile have any internal polices that limit you on how frequently you can be a “returning customer ” in some arbitrary period? Has anyone left/returned to T-Mobile more than once? Twice? Three times? In a short span without issue and letting you get back your tenure/plan each time as long it’s not past 90 days?

Since promotions are hard to come by without bill credits I’m willing to leave to a prepaid carrier then come back every so often for some change. I’m planning to port back to T-Mobile soon wanting to know if there is an internal clock on how many times you can do this and keep your original plan.