Quote Originally Posted by Rafaelfras View Post
That's why I said earlier that out of combat abilities have greater impact on the DM because he has to take then into account, while it is very simple to create options when they would be needed but aren't there
I think this is right, and you can see lots of places in various published adventures where the module writers haven't taken these abilities into account, or assumed that the players wouldn't use them, or forgot they existed entirely. It's a balancing act, and a very tricky one.

My experience, generally, is that it doesn't matter which character has the ability as long as all the players are contributing equally. Player A has the plan, Player B casts speak with dead, Player C composes the specific questions, Player D makes the rolls. Players A and C aren't rolling dice but they're equal partners in what's happening. What you don't want, and as a GM need to take steps to avoid, is Player A having no directly useful abilities and checking out of play until there's something written on their sheet they can use.