See i don't think there is any value in having those teams bash each other.
If manly get a week off, they will be fine for the next game and niggling injuries will get time to heal, any impact from the game will be treated and they will get to rejuvinate.
I don't think the week off would be that bad for the Sharkies, whilst i think momentum is a great thing, any injuries can occur in an additional game and they also get alot of time to rest and get mentally set for the next game.
I'd much prefer to only play 2 games to get into the GF than 3.