As far as I've understood they drive all of the stages twice (not sure about but at least once) before the rally and that's when the co-driver makes his notes... or improves the old ones, usually most of the stages are same as the previous year. Like corrected above the shakedown is completely different thing.
Also nowadays some of the stages are usually driven twice in the same day during the rally... which sucks.
Also nowadays some of the stages are usually driven twice in the same day during the rally... which sucks.