Do you ever start writing a song in one key, then after you have a fair chunk transpose it and realise that it sits way better in the new key?
i usually only change the key for the voc. for range issues. for example i was writing "outside" in D but then i came up with a bridge that wanted to go way down low so i moved the entire song to starting E to be more reasonable. regardless i always do key check before starting the recording, and often nudge it up a few for vocal brightness, because writing voice can be mumbly and low. key choice is all based on the vocal, but also let's be real also try to avoid the exact same key of the last song i just released