In the case presented, it does, because the whole idea that there is a challenge involved to is (4e SC or not) implies that there is something more going on in the scenario.
That is a point that bears noting - correct me if I am wrong, but the initial goal was to set the effects of passing through the swamp on the party, to determine how fatigued they are at the end, and so forth.
In making this into a series of encounters, that apparently grew into "something more going on". So, I am back to wondering if this solution actually fits what was originally requested. We might see a bit of scope creep here, but as we see later on, that actually leads to some resolution...
This touches on one of the reasons I don't think 4e is any better at narrative pacing and thematic play than PF (which was the original point), and may be even worse due to what I consider... rigid design in the SC's basic structure.
Let us look at the crossing the swamp scenario. In 4e, it could be handled by a skill challenge. It has been suggested that in 3e, it could be 3 non-combat encounters and one minor combat encounters...
...which, if I translate it to 4e again, becomes 3 skill challenges and a small combat encounter.
In 4e you could deal with crossing the swamp in light detail (one SC) or greater detail (3+ challenges), at the GM's whim, not the rules' dictate. In 3e you wouldn't need to use 4 encounters - you could do it with less. In either edition, the level of detail, and thus the pacing, rests not in the rules, but in the adventure design in the first place - like it always has!
Mind you, I don't actually think there's anything new in the skill challenge. The SC is just a clarification of what I used to consider a non-combat scene, putting extended use of skills to solve problems into a framework so that GMs can think a little more clearly about them. In practice, I don't find its pacing to be any more rigid than 3e non-combat encounters/challenges.