ValhallaGH
Explorer
On the other hand, certain skills (Hide, Move Silently, Spot) are so useful for adventuring that each PC will have a substantial number of ranks in them.
And ... ?
Believe it or not, those are all individual skills. The results affect the individual and cannot steal the limelight from another PC.
So, any actual concerns you have? UMD is limited by wealth and availability (both under the DM's direct control) so that skill is manageable.
What I would be worried about are the "I win D&D skills," also known as Bluff and Diplomacy. With max ranks, max synergies, and a couple of feats, characters can reasonably have a +10 to +20 in these by level 2. That is something to worry about, the ability to use a single die roll and a few words to end every encounter that's not against mindless creatures.
Never forget the power of speaking well.