A sample of skills that a solo diver doesn't utilise:
1) Gas switching drills
2) Multi-gas dive planning
3) Decompression procedures
4) Line laying
5) Penetration procedures
6) Accelerated decompression
7) Hypoxic gas considerations
8) Lost buddy procedures
9) Cave rescue procedures
10) High O2 procedures (analysis, marking, storage, filling)
and so on and so on and so on.......
You make some good points and I don't know if solo diving is technical diving (seems there is debate as to whether technical diving is technical diving) but I have always approached solo diving as if it were technical diving. This probably has something to do with my region (cold, low vis water) and the fact that it wasn't a spur of the moment idea for me.
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What I didn't add in my previous post is that, although I did solo on dive 21, I had been solo climbing, solo wilderness backpacking and solo canoeing for 20 years before that and had developed a good sense of what was acceptable and not acceptable risk.
For quite a while I pre planned even my simplest solo dives with certain self imposed parameters that I would not violate (like a tech dive). I limited my time, drew my routes on a slate, limited my bottom depth etc... In wrecks they do progressive penetration (sometimes); I did progressive solo diving.
I also often solo snorkel in isolated locales and even limit my water time in those circumstances so I won't become incapacitated by hypothermia without knowing. Who does that?
Far from being exciting, my solo dives were/are boring, labour and equipment intensive affairs. Far more so than the casual buddy dives I see others doing. My current solo dives are just beginning to include some intentional mixed gasses (different nitrox blends) and again, I am back to those pre set dive plans I used to make.
My instructor, one who has had as many dives as you have had, has done basically everything you can do diving, and has been certified since 1963 GAVE ME THE OKAY FOR SOLO DIVING.
If he said you shouldn't would you stop?
It doesn't matter what your instructor says, he won't be there with you when you dive. Someone ready to solo does not rely on some external source to validate their decision. Period...
...and that can be a lonely position to hold.
What I learned from climbing is that nobody
really cares if you solo, except for a drunk girl in a bar perhaps, and everybody will think you're a fool if you die. You may get your 5 minutes of fame but it is fleeting. Someone will always come along and do something bigger better and bolder.
Whatever you do, give yourself time to approach your endevors like someone who intends to partake in them for a long time. Even if your experiences seem meager at the time, own them, know them and build on them. Leap frog is not a soloists game.