I reckon that what I've got in that paragprah sets out a pretty good system. It is one in which the players "figure out the best way to reach the objective with the party's skillset and minimal risk of failure and then execute said plan, adapting to failures on the fly." It is certainly not one in which players "repetitively rolling dice to gather enough points to proceed without any plan or intend to actually work towards the goal, with everyone rolling the highest skill s/he can get away with over and over, it doesn't matter what".
My experience with Skill Challenges from my discussion a the panel with WOTC R&D as well as the skill challenges that were approved by R&D during the first year of Living Forgotten Realms and a bunch of back and forth e-mails with Chris Tulach trying to get an idea of how to write them to make sure I wasn't doing it wrong amounted to this:
WOTC couldn't make up their mind exactly how they wanted Skill Challenges to work up to the very last minute. Some of the details changed in the very last draft of the rules.
Basically, they wanted a system that could fairly measure the "difficulty" of a skill encounter so you could give proper XP out for it in the same way you give out XP based on the difficulty of the monsters you face.
So, the idea was that knowing the PCs would have to roll 10 successes at DC 18, for instance means you can figure out the mathematical probability of rolling that many successes before failing 3 times.
That's the underlying structure to them. However, how exactly you could implement that and still be fun was kind of up in the air. Because at its core, the mechanic is "Keep choosing skills and rolling them until you either succeed or fail".
So, basically we were advised to use that as the structure of the skill challenge and then beef it up with flowery description to make it seem more than that.
There appeared to be a disagreement as to whether or not skill challenges should restrict skills very much or not. One group wanted skill challenges to be a large tree of expanding choices like a huge choose your own adventure. If you started at step A and chose to use Athletics as your first skill choice you'd end up at step B and you'd be in a different place with a different context for your next skill check. If you used Acrobatics, you'd instead proceed to step C and be at a different point in the skill challenge with entirely different options. Another group seemed to want to make it extremely open ended and really simple to write into adventures. So you could write it in a really short stat block and then leave it up to the DM to insert the flowery description to make it more interesting.
The second group mostly won out and there was some text left in the DMG from the old method of doing things because of how late it was changed. This meant that the DMG description of Skill Challenges kind of tells you to do BOTH of them.
Basically, the first way of structuring it is:
You need to escape from people. You reach a barrier. How do you get past it? Athletics to jump over it? Alright, you succeed. You are now running down a street and run into a crowd. How do you get past them? Diplomacy to convince them to move? Alright, you succeed....and so on.
The second method is:
There is a magical artifact that has gone haywire. It will explode unless you can turn it off. Thievery and Arcana are the only real skills that can turn it off. Keep making skill checks until you either turn it off or it explodes when you fail. It takes 10 successes to disable it.
Technically, there is a 3rd method as well that is the same thing just a bit more open:
You need to reach the end of the forest. There's nasty monsters, bogs, traps, horrible weather, and food and water issues. How do each of you contribute to the success of the party? You use Survival to gather food and water for the party? That's one success. You use Perception to keep your eye out for monsters and traps? That's 2 successes.....alright, after 10 successes you successfully leave the other side of the forest.
I've seen all 3 of these appear in Living Forgotten Realms adventures and official WOTC published adventures. R&D had the final say on all LFR adventures for the first year so they approved all of these as valid uses.
Most official skill challenges had primary skills that would always work and secondary skills which would have higher DCs or would provide bonuses without providing a success. There was a lot of debate amongst DMs as to whether or not you should allow skills that weren't on that list. The DMG says you shouldn't say no very often but you should say no if it is out of context. Some DMs would accept the flimsiest of excuses to use other skills for successes others would not allow any that weren't on the list.