This is something I've been pondering for a little while now. When you are in a competitive tournament, how far do you push the limit of being a nice guy? Does the answer change from round to round?
Reason I ask is that with Ritual of the Damned, my Dark Angels got a significant boost in their shooting. One of the defences against it is to use Prepared Positions. Where the issue comes is that Talonmasters give Ignore Cover to Ravenwing units. When half my army is comprised of Ravenwing units that will benefit from this, is it bad form to stop my opponent from spending those Command Points? Or is it expected that at a tournament, you follow the axiom of "Never interrupt an enemy when he is making a mistake."
On one hand, we as players will not stop our opponent from making a bad move or shooting the wrong target; so is it along the same lines that they are making a mistake with their command points?
Also, as I asked before, does the answer change depending on how late into the day it is? Are you more likely to tell your opponent to not spend those command points in the first round than you are in the last round when you are playing for the overall win? Does the answer change if you've been knocked out of contention?
*** Note: I am asking from a competitive standpoint, so casual / friendly views don't really help out that much.