I could be off-target here, but my overly brief sense of the main difference between investigation in many (most) trad games and investigation in something like PbtA or FitD is that the latter are not interested in dead ends. They either skip right past them or mechanically turn what might be a dead-end scene in another game into a surprise plot twist or revelation.
Does that sound right? In a sense, it seems like that's a main, overarching feature of Story Now games--get to the conflict already.
If you mean that in a more traditional game, where the GM has already predetermined who did it and what the clues are that may be discovered that will point the players to the culprit, and then the players for whatever reason are spending their time chasing info in a location that has nothing to do with anything.....then yeah, that should not be happening in a PbtA/FitD type game.
A traditional game doesn't care why the players are searching the billiard room instead of the kitchen or the conservatory, all the traditional game cares about is that there are no clues to be found in the billiard room..they're all in the kitchen and conservatory! I've played and run scenes where the players are just spinning their wheels trying to find something that isn't there. Eventually, once all the possible actions have been attempted and rolls made, the players will decide there's nothing there and move on. Or perhaps the GM may actually say "After exhausting all efforts, you realize that there is nothing to be found in the billiard room".
Which then may make you wonder why the GM didn't just say that at the start......and I think that's a good question. It's the kind of thing about traditional games that would frustrate me, and ultimately led me to looking at other games. Think about this.....the end result of searching the billiard room if you succeed at every roll is exactly the same as if you fail at every roll. Literally nothing has changed, and who knows how much time may have been spent on this. Different GMs may speed this up, others may let it play out as long as it takes....but either way, this seems to be a failing of that kind of system. Why waste all that time on something that won't matter?
In a PbtA/FitD type game, the GM is meant to ask the players why the PCs are investigating the billiard room, and then shape what happens based on those answers and on the results of the rolls. So they may still wind up finding nothing of use in the billiard room if the rolls don't go their way....but something will happen. The system will produce outcomes by prompting the GM to make moves or to inflict consequences. And if the rolls go well, then there will be progress of some kind, usually based on fiction that's already been established or by the players' stated intent of their actions.
In this way, I've found that it kind of works opposite from the traditional approach. Instead of the GM determining details ahead of time, and kind of determining what skill and what result may be needed to learn the information, instead the player makes a move or chooses an action with a stated goal, and then the GM determines the details based on the chosen move/action and the result of the roll.
Now, I don't think that the GM cannot have any possible ideas about how things will go ahead of time. He may have a feeling for who the culprit may be (based on previously established fiction, mostly). And so he may fold that into the results in some way if it makes sense to do so. This last part is a subtle but significant distinction, I think. @Fenris-77 hints at this kind of thing above with his comments on the duke and his diary.
All of which is a long rambly way of saying yes.....get to the conflict already is a deliberate element of these games.