You want to... reflect on a Mario level? Really?
I'm not on a mission to finish the game as fast as possible, but I don't start my new job until December or January, so I have quite a lot of time until then. Why would I let the game just sit there when I could be playing? Just because you let a game like this sit down there, it's not gonna get any better.
I'd be surprised if most of GAF didn't do this too. You got a game you've been waiting for so long, and instead of playing it as much as you can, you "reflect on it and then get back into it"? Really? This is a platformer, not an RPG
Also I'm getting all the medals and pretty much trying to 100% the game, so it's not like I'm even rushing it.
Oh, and one more thing. I'm getting through the game itself so fast because really, there's nothing else to do in the game but keep playing levels. If this were, say, Skyrim, I would still probably be near the beginning because I love exploring (plus, I can use it as references and inspiration for my own 3D stuff). But there's not really much you can explore in a Mario game.