Jeeez, if everyone had to play every repetition of a given tune exactly the same way every time, why would we bother to play, or for that matter even listen to each other? We'd just agree on the definitive "correct" approach, identify the recording on which it can be heard, and never allow anyone else ever to attempt a new approach!

Before the invention of recording media, of course, every player played every tune his own way, more or less, and no one was aware of any single "standard" version. The supposedly "traditionalist" idea of song-version orthodoxy is really a modern, 20th century phenomenon, possible only after recordings could be made and distributed.