Hi,
For example connected MetaMask to Revoke Cash security utility, when venturing into established/reputable De-Fi sites like Uniswap via your MetaMask wallet and signing/confirming transactions shown on screen in metamask, why is it by default for every transaction that the approved limit is set to Unlimited/Max and to revoke this it cost gas fees

If I do not revoke and do not pay the gas fee to revoke past smart contracts then I am open to smart contract risks/hacks correct?
When transacting on De-Fi sites how do I set by default for the every Approved amount Limit to be auto adjusted to the amounts I want to just deal with? For example if I want to swap $100 USDC into $100 USDT on Uniswap then how do I auto set it to approved limit of $100 only not max/unlimited because in future I might forget about this past swap and lets say for example in future I deposited $1million stablecoins into Metamask and forgot to revoke the unlimited/max amount approval for the past $100 swap I did. Because I forgotten I risk losing $1Million

?
I don't want to keep on paying gas fees after every de-fi transactions to revoke past no longer needed smart contracts.
If I do not revoke past smart contracts approval amounts then this is still open and can be used for future transactions on the De-Fi site meaning if I do revoke past contracts then I have to pay gas fees again to set up a new smart contract approvals amounts on the same de-fi site like uniswap?
Also what are Signatures in Revoke.Cash?