[hiddew]

Why not? A branch is a pointer to a commit, so the commit built for staging can be the same binary that will be deployed to production, if the production branch is updated to point to the same commit as staging was pointing to. No rebuild necessary because it is the same commit.

[Uvix]

If you have fully reproducible builds, and if it's from the same commit, then it's probably okay. With multiple branches in play, and staging built from a different branch than production, the latter doesn't hold.