What I’ve seen is that when I raise my bids, I show for more variations, and when I lower then I show for less. So, usually when I lower them I don’t show for different variations in most cases, just a smaller subset of what I was showing for.
With broad match, trying to measure the true effectiveness of all those keywords variations at various bid levels is about impossible. You could do it if you have waaaaay to much time on your hands. I think you’re better off adding the exact/phrase/modified combinations so you have more control over the display and setting your bids at those levels.
As far as needing: brown shoes, shoes brown, shoe brown, brown shoe all in broad match – that goes to the heart of AdWords – how much time do you have?
If you really want to show for something – then add it. However, it gets to a point where you are adding so much stuff that there’s no reasonable way to measure and bid on items without losing site of something else you’re working on (like testing).
Usually, I don’t bother with every possible combination of broad match. I usually start with one combination; and then as I find the actual queries, I add those as keywords so I can set bids based upon the query and then let broad match find new words for me.