Why can bands play for hours often utilizing different instruments without ever looking at sheet music, but orchestra musicians always read from sheet music?

Question

I saw a clip where a pianist was playing and someone was turning her pages for her, but they fumbled and dropped the sheet music. The pianist kept on playing, but it got me wondering why have the sheet music if she knows the song anyway. Do they really need it? Why can’t they just learn the songs like all bands do?

In: 5311

Answer 1

My parents neighbor plays in the National Philharmonic and for most concerts plays the piece for the first time live on stage from the sheet.

Only the main series elite concerts or special events (a big composer or new difficult piece that will be recorded live) has a rehearsal. Single.

They have mastered the craft, they don’t need to learn a piece to perform it, but as they cannot remember so much single instance pieces it makes much greater sense to be an expert reader rather than memorizer.