I am not very knowledgeable, but your question is kind of related (maybe) to the one I was about to post, so I will piggyback on your thread:
I bought two new azaleas last spring, and they came from the nursery in that dense, "lush" ball shape you describe. I assumed it was from how they were pruned by the nursery (perhaps to keep them small enough for their pots until sale).
I am wondering what the pruning strategy is to get them to develop a nice, natural, more open shape like the mature azalea that came with my house and that I've been tending for 8 years. I have never done more to that one than dead-head it and remove a few errant twigs here and there. It is in a very shady spot and has grown slowly.
I am just wondering whether there is some shaping work I have to do to get the new plants to look "natural," or whether they will actually just naturally develop that way.
So I hope some real azalea experts will stop by this thread with some pruning advice.

Many mega-nurseries have machines that go over the plants and prune the tops off the plants to encourage the bushiness once or twice when they are young. They also force feed to get the lush growth with lots of flower buds. It is totally controlled for that optimum look at point of sale. It is all machine done, not hand pruning. It is not something that is recommended for a plant grown in the open and exposed to the elements.

Here is a link that might be useful: How to grow rhododendrons and azaleas.

Thanks for that informative link. It sounds like I don't have to do too much to encourage a natural shape to develop, just tend as I've done with my older plant and the sins of the grower will soon be forgotten.

BTW, I always thought that deadheading was strictly needed, and it has sure made a huge difference in how mine has bloomed, but perhaps that's because its location is not great--very shady.