As a spearo diver, most of my dives are solo dives, thou we jump out of the boat as a team (2 hunters), we usually separate after a few minutes dive, both of us are very well seasoned divers and have all the necessary gear to rescue ourselves, extra air, Epirb, z-knife, sausage, small flair kit, etc.
I feel that short of loosing consciousness, I can deal with any situation that may arise and rescue myself, also we dive very conservatively and many times had called off the dive due to not appropriate conditions or just a hunch.
When I get to dive with other divers, normally they look to me as the leader due to my training and experience and usually end up not enjoying the dive due to the work keeping track of all the group, that's the main reason I try to dive most of the time with my fellow "buddy" hunter.
When I dive I do it to get away from the daily grind and relax myself in an activity that I enjoy very much, that's why I have rejected many times the invitation to become an instructor, as an instructor, I'll log many dives, but it would be another job and the fun and relaxation will go away.