At some point you need to stop asking questions and running sticky note exercises. Sometimes you just need to start designing the damned thing. If there’s one lesson we can take from Lean UX it’s this; you can often learn more from a bad first prototype than you can from any number of sticky note exercises.
In truth, these exercises are rarely for the benefit of the client — at least not immediately. Instead they are a means for design teams to understand the problem and present it back to the client in order to build consensus. “This is the problem you have, these are the challenges we all agree you face, and this is where we’re going to devote our efforts.” In this situation the agency is the immediate beneficiary. The client only benefits once synthesis has happened.