All of that is great. I do expect that you knew most of this and the course would have been a lot of mentoring, especially with skills.In no particular order other than as-they-come-to-mind:
- Good principles of redundancy. What counts, what doesn't, what's needed, what's not.
- Formal dive planning, including gas calculations. They hadn't been required in any of the courses I'd taken previously.
- Mindset. Solo (and later, technical) diving requires a different mental approach than buddy-pair recreational diving.
- Practice recording data on a slate.
- Practice deploying a DSMB.
- Ability to handle an emergency solo. And I actually had one; one of my second stages went bang! and fell off. (Thanks, LDS service-monkey.)
- Knowledge that diving solo isn't an automatic disaster.
- Increased self-confidence.
My Solo Diver course was very memorable, not from the skills, but from a lot of the “bleeding obvious” things that were explicitly spoken about during the lectures. Many times the thought, oh, of course, came to mind.
Hope you’ve had many enjoyable solo dives since the course

My current “bleeding obvious” thing to watch is the beginning of a new season. It was only a few months ago that one was diving with impunity. Then there’s the winter layoff and it all begins again. That’s when the cock-ups hit big time; from forgetting the drysuit hose through to mis-clipping stages, too much/little weight, being slow to kit up on the boat, forgetting the left-handed spod rod, etc.
Start slow; work up to the big dives.