Today I beat NSMBW in one sitting (took me 1h20m according to Wii notice board thing). That's one of the first times I've done so, iirc my third game beaten in one sitting after SML1 and SML2 (which aren't that long games anyway.) When I was younger I kind of knew about the warps but didn't use them much. After watching any% speedruns I learnt the optimal route and beat it by warping from 1-3 to 5-1 and 5-boo to 8-1, also 8-2 to 8-airship with 8-7 in the middle.