Actually there are quite a few repeats in the campaign but they were different enough to not make them too repetitive.
1.Leon/Helena and Ada have similar paths in the underground lab 2.Jake/Sherry cross paths in Europe with Chris which was pretty much the exact same 3.Ada and Chris cross paths on the ship, again really similar 4.Jake/sherry cross paths with Chris/Piers during the ambush but they are different enough to be unique, both battle the chopper. 5.Chris/Leon cross paths when chasing Ada which are identical. 6.Ada/Leon cross paths fighting Simon...Ada's helicopter scenes are terribly boring 7.Sherry and Jake cross with Ada during the raft sequence. 8.leon/Helena and jake/sherry fight the big bad of jake's campaign after the crash
Can't argue that there are a lot of similar scenes but I can argue that they are not repetitive because each sequence with a different character has some unique properties that the other one didn't.