Grog said:
As Remathilis pointed out, if the party rogue decides to scout out an area by himself (because he's the only one who has a chance of staying hidden), that basically amounts to a solo adventure for the rogue while the other players twiddle their thumbs.
That most certainly is not a player problem.
Wait a minute here. It might not be a player 'problem' but it is a player decision. The DM doesn't decide whether the whole party or just one rogue is going to scout out something.
You can pretend all you like that this has to do with disparities in skill levels, but its nothing of the sort. It's the inherent nature of scouting that small groups draw less attention to themselves than large groups. Even if the entire party was sneaky rogues, it would still be a perfectly valid choice (and maybe even the safest choice) to just send one player character in on a scouting mission.
Suppose you have a party of 8 sneaky rogues, and each has a 95% chance of sneaking into and out of the camp without being noticed.
If I send in the whole party, that's a 33% chance that we will rouse the camp. I'm far better off sending in just one sneaky rogue (preferably the sneakiest), so that I have a 95% chance of mission success. If I absolutely need more than one rogue for some reason (maybe I have to carry out something heavy) I'm going to choose to send in the minimum number of players to carry out the mission because that's the smart thing to do. If something goes wrong, then I'll try to sneak in with whoever didn't go the first time to rescue the first player/group. I'm not going to go, 'Hey. Let's risk a campaign ending TPK because its not fun for some of us to wait for an hour while one guy does his thing.' And if one of the other players suggested that he wants to risk the mission and the party and possibly the campaign because its boring to stay behind, I'm going to percieve that player as being a serious liability.
The fact everyone is reasonably likely to succeed does not inherently turn an individual challenge into a group challenge. Just because everyone could theoretically climb the wall, doesn't mean that you don't send one guy up first and have him throw down a rope for everyone else. To force it to be a group challenge there needs to be some additive rather than subtractive value to more people (odds of success have to go up rather than down, as almost never happens on a stealth mission), and usually there has to be a tightly constrained ammount of time to complete the task. And to force it to be a skill challenge as well, you have to have a situation where less skillful classes don't have a stronger alternative solution which more or less gets around the need for skill ranks completely (for example, turning invisible, flying, etc.)