I began solo diving on dive 21.
Some thoughts I have on the subject:
I see soloing as a specific type of diving like cave or deep wreck diving, not as something a buddy diver does more or less on the spur of the moment.
I follow a graduated approach to soloing with specific goals and skills to practice and incorperate and generally take a technical approach to recreational diving. Most of my soloing is done in isolated locales (coldwater, low vis.) and I am usually the only person (diver or not) around).
I (currently) limit my soloing to 100' mainly to avoid the effects of narcosis.
There is basically one wild card in solo diving that I know I cannot control; a medical event at depth (LOC, heart attack, seizure etc...). If something like that occurs I accept that I am dead. However, I also think that when something like that occurs in a buddy situation the diver is almost always equally dead.
The actual "dive" skills are basically the same as with buddy diving but more emphasis must be placed upon them. Bouyancy, gas planning, navigation etc... The diver must become "a diver" in the older sense of the word.
While much emphasis is placed on redundancy (good to a point) I think a far greater element to focus on is situational awareness and the ability to avoid problems before they occur. When you are entangled you will or will not cut your way out and when you are OOA you will or will not find an alternate air source. The skill to develop is not to become entangled/ go OOA in the first place.
I have other thoughts but it's late and my wife is calling.... Hey, I'm not solo in everything I do
This is a great response! I think situational awareness & becoming a true "diver" will outweigh quantity of dives. I guess it's like the old saying quality over quantity and we each have our personal choices. Thanks for sharing your insight!