Normal lengthed SMBX Levels

[Vellidragon]

Nintendo Levels are usually 1-4 Minutes Long... can be longer or even shorter than that but often by that direction.

Nintendo's level lengths are somewhat proportionate to the number of checkpoints. Super Mario Bros. 3 has very short levels, but it also has no checkpoints. Yoshi's Island has fairly long and complex ones since it allows for any number of checkpoints (in addition to having fewer instant deaths). Super Mario World's final castle is a good example of such considerations at work: Nintendo designed a lot of rooms for it, but only a few have to played in one session since the single-checkpoint system (that SMBX shares by default) would make it frustrating otherwise.

I think common sense should be applied for level length. Putting oneself in the player's shoes is essential here. Would it annoy the player if they die at this point and have to restart from the beginning/checkpoint? If so, a shortening or at least reduction of difficulty is probably in order. Players want to be challenged, but not tortured. Ideas cut from the level that way can often safely be transferred to later ones as appropriate.

[Superiorstar]

*bragging intensifies*

I doubt you'll be able to make a 4 hr long level appealing and fun all the way through, especially with the block limit.
Also, the CC8 judges sure were lucky you decided for something rational.

Not to burst your bubble but he did actually make a level that was around 4 hours, not kidding.

[icez]

3-7 Minutes To give a player a enjoyable experience with out dragging it out to long i would give like a final level for an episode probably the 8-15 minute just because it is a final level after all

[4matsy]

I don't think about level play time much; instead, I usually make the average level (or, at least, level section. Or sum of level sections...depends on the level) about 20 screens long, putting the midpoint in at the closest available point to halfway.

Seems to work fine most of the time. *shrug*

[JupiHornet]

I personally think that the way people design depends on how they play. If they are really good at a game like this, the levels they make tend to be longer and harder, and vice versa.

My levels usually take 3-5 minutes to beat