The below post was written under the assumption that OP is using bitcoin core.


Newer wallets are deterministic and require a single backup. Older wallet files have (by default) 100 private keys pre generated from you, so you dont have to update after every new address. Depending on how much you use the wallet once a month/week should be enough. To see how many keys are left you can use getwalletinfo in the dev console. You can use the same command to see whether you have a HD wallet or not. HD wallets show a line masterkeyid, older wallets do not.

-> https://bitcoin.org/en/developer-reference#getwalletinfo