Beware the 'bunching'
 

Beware of bunched aces in hold ’em. By Mike Caro :news:

I call this the “bunching factor.” It has nothing to do with poor dealing, though.

If you’re playing 10-handed hold ’em and the first seven players have folded before the flop, there’s a better-than-usual chance that the few remaining players hold aces. Why? It’s because when opponents fold, it’s more likely that they folded something other than aces.
More aces left

This means that statistically there are more aces left that could appear in the few remaining hands. This isn’t an overwhelming statistical factor. But it’s significant enough that you should be more selective about the hands you raise the blinds with from the button (dealer position) when everyone else has folded than you would be if the deal began three-handed!

This “bunching factor” applies to other high ranks, not just aces, although the effect is more diluted. It’s also applicable to other forms of poker, such as five-card draw. — MC :flyaway: