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?
Encryption? No, others have good explanations on this.
Password hashing? Interestingly yes! Passwords hashed with bcrypt are often hashed 10, 12 or more times over! With argon this is usually also 4 or more times!