That's actually unrelated to the main topic, but I'll give you a quick answer. If research and ratings show that a particular format is dying in the market and tweaking it won't help, the next question becomes "what format holes are there in the market?" and/or "is there a format where the existing station is weak enough that their audience is potentially ripe for stealing?"
Either of those questions will likely trigger research designed around the question. It may also involve focus groups to determine what formats the listeners feel are either poorly or not served, and in some cases may be used prior to deciding which question to research in the first place.
Sometimes, it becomes a corporate decision. Other times, research as I have described. Or it can just be at the whim of a local station owner.
In any event, the process is not a "narrowcast" of music research surveys, as you imply.