I don't think its common for people to try to "memorize leetcode."
Most interview loops at places that do algorithm interviews are 2-3 rounds and each round will have up to 2 questions. Its very very unlikely the interviewee will only encountered questions they have memorized.
More likely, the interviewee encounters questions similar to ones they have solved and they know the pattern around solving, then are able to apply their learned skill to the new problem.
Similar to your music analogy: you can absolutely be a strong guitar player in a band if you just memorize a few different chord shapes and can apply them up and down the fretboard to different keys (lookup the "CAGED system").
Most interview loops at places that do algorithm interviews are 2-3 rounds and each round will have up to 2 questions. Its very very unlikely the interviewee will only encountered questions they have memorized.
More likely, the interviewee encounters questions similar to ones they have solved and they know the pattern around solving, then are able to apply their learned skill to the new problem.
Similar to your music analogy: you can absolutely be a strong guitar player in a band if you just memorize a few different chord shapes and can apply them up and down the fretboard to different keys (lookup the "CAGED system").