I think your example refers to pacing. In other words, how you lay out your challenges.
Some platformers can be seen as a collection of challenges laid out in the same world. They could technically be broken down into smaller levels including a single challenge (jump over a hole).
The "dead zone" in-between these challenges is a byproduct of attempting to collect them in a single entity.
Games such as Contra 3 leave very little time for you to be safe, whereas, games like super mario bros 1 will be a bit easier to grasp.
The advantage of having natural "pauses" is that it allows you to let the reward sink in: you've completed a challenge, and can now rest temporarily. This causes a chemical loop in your system, and after a while, your body adapts to stress and relief.
The advantage of more intense games is that it will only reward you at the end of the level, forcing you to be "in the game" for longer gaps. As a result, the stres and relief loop iterates much more slowly and forces you to commit to a longer period of time for each of your action (inherently being more immersive).
You'll notice that there are often tricks used by developers to minimize the breadth of a "relief zone". For example, in super mario bros, the mobs will move horizontally, covering large patrol areas. Though they may not be very big threats, they still force you to stay alert to avoid a cheap death. Some levels also automatically move forwards, forcing you to always be on the run. You might notice that you like/dislike these particular levels. There are various other tricks you can use to affect pacing.
My suggestion would be to try to design your levels as a collection of challenges that you believe are inherently interesting. Don't make them too complex.
Then, add in a few gameplay ingredients to tie them into one another so that it doesn't look like a series of challenges (moving monsters might help here).
Then, use tweaks to affect game pacing until you reach a balance between difficulty and boredom that you believe is adequate. Understand that the game will always be too hard/easy for some players, therefore, having people from your target audience test the game. Is it too hard/easy for THEM?
It is important to know the skill level of your testers, and to know your target audience.
Good luck.
EDIT:
Other examples that came into mind:
- In castlevania, the medusa heads are used to insure you have no respite. You'll notice that some players become irritated by this, whereas others appear to have mastered this extra challenge layer. The advantage of this particular challenge is that it is not bound to a segment of the level, and allows you to eliminate "safe zones" altogether, as would panning the camera.
- Also, in Castlevania (SOTN), you'll notice there are a lot of safe zones, especially in the first couple of rooms. The game clearly wants you to get comfortable with your controls. As you progress along the game, you'll notice that there are much less such zones, but aside from loading portals, there are still rooms which are safe (clockwork). The idea here is that Castlevania implements other types of challenges which are not inherently skill based. The layer of "exploration" of that game brings in other types of challenges (puzzles could also fill in this role). The relative "safety" of these areas is counter-balanced by another layer of gameplay: creative thinking.