Strange question.... let me flesh it out.
I recently switched to Speedplay pedals. I have a significant leg length discrepancy, so the first order of business was to shim one side. I was in one LBS and they had a pack of the BikeFit wedges so I snagged it. To do a simple length-shim with those you would stack them on top of each other with the wedges reversed. An hour later, I'm in a different LBS and they had regular 1mm straight shims for Speedplays, so I bought those too.
I've got the leg length shimmed to my satisfaction, and am thinking I'd experiment with some side-wedge-shimming just to see what it did for me, since I already spent $30 on this pack of the dang things <g>... This is how I've fit myself to my bike; make adjustments, take the bike for a 50-mile ride and see what my body tells me. I do bring the tools along to hit the "undo" button if a change is causing problems.
So, to my question. The pamphlet that came with the BikeFit wedges unfailingly shows them installed with the fat side to the outside of the foot. Is that "most common"?