As a professional mechanic (Diesel) I can assure you that while 6 point sockets are an absolute neccessity in instances where considerable force is necessary, the sockets in my set that see the most usage are indeed 12 point. Much easier and faster to use, not to mention the fact that I have seen too many instances where side clearances and smaller turning radius dictate that a 12 point be used. Each type has its place and if I only were able to own only one it would have to be a high quality 12 point set. Just my opinion formed by years of actual experience.
As a practical matter, I regularly interchange 5/16=8mm,7/16 =11mm,1/2=13mm,11/16=17mm,3/4=19mm & 7/8=22mm in instances not requiring extreme force and vice versa (in some instances, substituting provides an even tighter fit) I know, right tool for the job!!! ;)
P.S. I hope you got that damn bolt off!