Solaris tried something like this for a while. While their competitors were releasing versions 4, 5 and 6 of their OS, Solaris was releasing version 2.4, 2.5 and 2.6. This made it look like they were just doing minor updates to Solaris, when they were in fact major new versions. Eventually they gave up and renamed solaris 2.7 to Solaris 7 just to keep up with the version numbering.