It's not just the versions of the plugins you have. The number of shells you have also depend on how many Waves plugins you have as well. For example I have two shells for V10 and one shell for V9.92 and one shell for V9.7. I believe this is because there is a limit to how many plugins a single VST shell can support. So Waves actually makes multiple shells on your computer depending on how many plugins you have. So the number of shells you have can vary greatly.
In my case my 9.7 shells contain only StudioRack (3 plugins total due to stereo/mono versions)
My 9.92 shell contains all my v9 plugins (85 plugins total)
My first 10.0 shell contains 276 plugins, my second 10.0 shell contains only 3 plugins (the Abbey Road Chambers which I just added).
I assume if I were to add enough V10 plugins I'd get a third V10 shell.