I agree. I've described here before my introduction to drysuits: I expressed to a friend (who happens to own my LDS) my desire to one day dive a drysuit. He then loaned me his, we reviewed what *not* to do (I had already been self-studying drysuits), and the very next weekend I went off to a corner of a local quarry to sort things out while he taught an OW course in another corner. This was ca. 1988.
My introduction to doubles was just as spontaneous and unremarkable: I had just returned fresh from my four-day NSS-CDS Cavern and Basic Cave certification courses at Ginnie Springs FL (single Scubapro 75.8? cu ft tank, Y-valve, Scubapro Stab Jacket, Scubapro Mk 10's and Balanced Adjustable and G250 on a 5 ft hose, lantern grip UK 500, Ikelite Mini-C x 2, DR reels). I stopped in at the other local dive shop and purchased a pair of used doubles tank bands made for Al 80's and a plastic backpack. I fitted my PST HP 80's (!!) as independent doubles to my SSJ, and next weekend I went diving with two full cave-certified friends. Per prior agreement, when I reached my training limits, I waved bye as they continued on, and I surfaced. This was in early 1989. I took my initial open water course in 1986 and was certified in 1987.
Anyone who knows me will testify to how cautious and risk averse I am. And how thoroughly I prepare.
While I don't recommend anyone ever doing what I, myself, do, I'm completely comfortable doing the things I do, learning things on my own. And people who know me, experienced divers I sometimes dive with, are comfortable, too, with my choices. In this respect, I'm no different from other divers I know.
None of this stuff is all that difficult at this level. None of this stuff at this level absolutely *requires* formal instruction. Caution and attention to detail and an honest understanding of one's own limitations and experience level are sometimes all that is required. And common sense, too, maybe.
I'm always a bit annoyed (to be honest) when people on here are so quick to insist that someone undergo formal training for this or for that when he/she simply asks a question! On-line scuba communities were not always like this. (Does anyone here remember Jim Cobb's Tri-Mix page?)
Safe Diving,
rx7diver