>>714499810
>30 seconds long
Yes, that's a good thing, because levels come as a set. You beat 3-4 levels plus a fortress with no game overs and your progress is locked in. SMW ruined everything by changing this, making levels much bigger and longer because you can just beat one at a time and then save the game, making lives and game overs irrelevant.
2D Mario went downhill after 3.