If you are going to store the several paper wallets in the same place (in your example, a safe box), it won't provide extra security. You either lose all your bitcoin in your several wallets, or you don't lose any of your bitcoin.

To make the paper wallets even more safe, you can employ BIP38 encryption (you need not only the paper wallet but also a password to spend the bitcoin) or create a m-of-n wallet and store them in different places (you need to have at least m different pieces out of a total of n pieces to spend the bitcoin).