In fact, you do not need to revoke every time. unfortunately, there are Gas fee for every transaction, then you should choose wisely where to Revoke. Farms that you should consider to revoke are, farm with no Accredited from the auditor, Farm with ultra-high yield. Or to be precise, you should revoke your standard Coins and Tokens (e.g. BTC, ETH, BNB, BUSD, BUSDT, DAI, USDC), for those governance tokens, they are ok to just keep as it is. Since once you no longer deposit into that farm, you will no longer need that Governance Token. Even you leave Unlimited allowance, there is no Tokens in your wallet.