I've always wondered how Nick and Agama managed to make such great tilesets. Then I realized. I've always drawn my tilesets the wrong way.
Because of my mental insanity I've always drawn either pixel per pixel or with the line/curve tool. That's where I got it wrong. Mentally sound people draw their tilesets free handed. My obsession for details has slowed me down a lot. I mean, it took 3 hours for me to draw the hills in my latest tileset. Nick and Agama would have made it in 5 minutes, and it would still have looked good.
In fact, even my obsession with Jazz Jackrabbit is probably due to my mental insanity. If I were mentally sound, I'd have conformed. Young adult boys like things like soccer, dogs and cars. I never really liked those things.
Another thing I realized about Jazz Jackrabbit 2 is that it was originally meant to be played in 320x200, and the 640x480 resolution was probably made for splitscreen mode. The reason why I think so is the 10x7 tiles wide background images in some levels, and the fact that every background layer fits the whole screen in 320x200, as you can see from the following pictures: