Well, the same applies to all UW photographer.
I am no diving alone whenever I can, or with my girlfriend who is sometimes modeling for me.
I was in Spain last week, in a diving center managed by friends and they never asked me to guide a dive or assigned any buddy when my girl was not on board.
I worked there as a scuba instructor and they know me, so I do what I want.
As an instructor, you also dive solo when you lead a group of 4 newly certified divers to depth below 40 or 45 meters... If anything happens to you, you know that they can not manage the situation.
So I dive solo with my UW gear in premium condition, and a 15 liter.
Even in Coco, I considered myself as a solo diver. With difficult conditions, if you also have to manage a buddy, your rig, the dive parameters... you don't take any shot.
Damien