Perhaps they've changed things. I was originally told that they had to generate a build for each unique configuration. Now maybe that was just in early days... it certainly sounds like a tedious way to do things.
Nevertheless, it's possible that there's a combination of hardware out there - various revisions of various modules - that has a problem they haven't figured out yet.
I believe that this is true. I understand they select beta testers by configurations of their vehicles as they experience different 'bugs' with different configurations when they produce a new generation of firmware. IMO (could be wrong), 5.11 probably fixes a problems with a certain configuration.