"realising that there are a wide range of interests and preferences and not trying to cater for all of them at the same time - that's how it used to work anyway."

The old models do not usually work when it comes to radio audiences. Tastes change.   Jim is right about not trying to be everything for everyone, but shows can be diverse and interesting to casual listeners as well hardcore folkies. There are some specialty shows that narrow their focus, and they are very good, but they usually will not last long. It has been said that listners tune in for 20 minute clips, and "regulars" tend to listen to certain shows for 2 years before moving on to something else. I think folk audiences tend to be a bit more loyal, but the narrower the focus, the less chance of long term survival.