If we consider information to be safe if we encrypt it (e.g., text in a file, encrypted with modern strong encryption), would it be safer (as in harder to crack) if we then encrypted the encrypted file, and encrypted the encrypted^2 file, etc.? Is this what strong encryption already does behind the scenes?
I only partially agree. Currently there are many algorithms wirh some expected to be more quantum resistant than others. So if you arent sure which one is actually the best, you could use all the good candidates on top of each other and increase your chances to have used at least one that is actually post quantum safe.
But yes with current year tech there is no point really. In the end you will just fall victim to the wrench>kneecap attack anyways if your secrets are big enough.