Currently, there is no way a user can control whether a particular collection should be balanced, while others should not be.
This way a user can say, collections which will possibly take less time to balance should balance first and then the others in ascending order of time taken for balancing.
Or the other requirement can be that Collection A has higher priority over Collection B for balancing. There can be any number of reasons why there should be priority for balancing.
Is it possible to add this feature? It may be minor but makes the server more controllable and gives more power to admins/users