I know exactly what you mean: I had a similar experience when I began doing LF a few months ago---I started off just sort of winging it, and my first batch of negatives came out perfect. I didn't even have my Combi-Plan yet; I just sewed tubes out of nylon screen, squeezed my negatives into them, jammed them into the cannister I use for 35mm, guessed the times and agitation, accidentally did everything at 72 degrees F. instead of 68, and had no problems at all. But I knew that in my case this had to be dumb luck, so I figured "if at first you succeed, try to screw it up next time or you'll never learn anything." Since then I've done a lot of screwing up, and I'm finally getting to the point where I know some of the parameters and can get consistent results (for example, no matter how much I brush and blow out my film carriers, I'm very consistent at getting that one pinprick scratch somewhere in the sky on just about every sheet).
What I'm worried about now is related to bvstaples's comment that "you'll never go back." I've suffered enough format drift (from 35mm through 6x9 to 4x5) to know that I could be in serious danger of going larger. I believe 4x5 is the largest practical format for handheld shooting (if this isn't true, DON'T TELL ME), so my refusal to use a tripod is the only thing keeping me from falling into the ultra-large-format vortex. I can easily see myself moving to 8x10, 16x20...before long I'd be driving around in a truck with a giant view camera mounted on the bed. I know 8-ft. x 10-ft. glass plates make perfect sense to a lot of APUGers, and I deeply admire all of you for it, but I have a family I'm supposed to feed and spend time with, and anyway it's really hard to park a truck in midtown Manhattan.