Yes, that is correct.
It is highly advised to make a new backup after each mandatory update, or each time you create a new receiving address. If you want to further bolster the security of your funds, you can also get the private key for your wallet address. That way, even if you lose the wallet.dat you can import the private key using the debug console and still have access to your funds.
It is the same with the private keys though, there will be one key per receiving address.
yes, the back up literally saved my ass when I decided to put the password to wallet. I used team speak for that procedure ( never! repeat! never ever do it it trough team speak!!!). so I setup the pasw and when tried to access wallet I failed. I tried everything all letters up and down and so on!! no luck! Team speak must have misspelled something((
so I recovered wallet from back up and setup the pasw directly from PC with a wallet, and it worked like a charm! so this backup really got me out of a trouble, so always use it before you gonna change something, it could save you!