And, a revision is supposed to be less than a 50% change to the planogram with no fixture changes. But I've seen revisions with up to 90% changes.
If doesn't matter from an hours view because those larger changes are reflected in more hours to set them are given in the adjacency.
The problem arises when most people assume ALL revisions are small and easy. This is true most of the time, but not always.
About 7 years ago, there was a 19 hour revision for L'Oreal. Even to this day, they'll sneak in large, over 50% change, revisions.