IMO really boils down to what the GM is using sneaky-stuff checks for.

If it's something like AD&D's Hide in Shadows, where it's the ability to remain completely unnoticed, even while being directly looked at, effective invisibility, then it should probably be very hard. If it's sneaking right past an alert guard, again effective invisibility but this time with movement, it should also be very hard.

If it's generally being sneaky but not doing something almost magical, there's no reason it can't be the group's pointman (different from a forward scout) making most necessary stealth checks and signaling the others when it's clear and when they should hang back. With some group-style checks in the more tense moments, as they all have to scatter for cover as a patrol gets a little too close, with the stealthier members helping the less stealthy. (Keeping in mind of course that too many checks for one mission will inevitably lead to failed checks.)