I put Galaxy on the shelf about 2 weeks after purchasing it. I had to wait quite a while after that for Brawl, so Brawl had nothing to do with it for me. I was actually hoping that Galaxy would last me longer xD
I think that games are more enjoyable if you beat them quickly and put them away so that you can come back and play them again. If you spend too much time analyzing every single thing, then you'll remember everything from the first time around and it becomes boring very quickly.