The topic reminds me of something I learned years ago when I sat in on a Master Class given by Leo Brouwer, a very dynamic figure in the classical world. His view was that
all notes in a piece of music (and arrangements), and/or performance, including what’s being labeled here as “filler”, should be considered important. However, some notes will carry more weight than others, and should thus be treated as “more” important. Those are the ones that need special attention and need to be flagged as such, whether you are composing, arranging, or playing.
I think it’s an important message to abide by. Ever since then, when looking over a new piece to play, I always look for those “1st tier” notes to give me a better idea on how I should approach playing them, along with the rest of the group.
Brouwer had an interesting analogy. When discussing a Bach prelude he said that a lot of the notes in this passage are like conventional gifts that one would bring to a party. A bottle of wine, chocolate, flowers. They’re all nice. But one particular Bb note in the piece was special, and needed to deliver a lasting impression to the listener. It’s not an ordinary gift. You’re not walking in with candy. You’re bringing a lion to the party.
Funny analogy, but it was a useful message imo.