We currently have 3 banks which I think is not enough considering the number of criminal gangs.
My suggestion is to double the count of banks and divide the amount of money you get from a single BR by 2. That way the economy won't be affected since the total income from BRs will still remain the same and gangs might finally stop fighting over banks, that means less bitch fight in teamsay!
We could possibly come up with potential new bank locations easily. Also if you haven't heard about the recent suggestion made by Zwolle, check it out here: https://saesrpg.uk/topic/4903/bank-interior-project
Those new banks could also be using that mapping from Zwolle's topic if/after he improves his mapping by the feedback he receives from SAES HQ and manages to get it live on the server.