Hmm...It's so hard to remember. I've been into it since my earliest memories, so a lot of it blurs together. I definitely learned the basics of how to tickle feet and ribs by being tickled. I think I learned a lot of the basics in terms of spots and techniques from being tickled, but improved those over time due to being tickle obsessed. Some of the spots I discovered on my own, or at least how to do it on my own were the tummy, thighs, and back. I clearly remember the first time getting my feet tickled by long nails and something clicking in my mind about better technique. Also rib tickling was not intuitive at all for some reason until it was done to me. Similarly, tickling behind the knee was that way for me. I remember in junior high, a girl tickled behind my knee when I was standing and talking to someone else. I would have been more embarrassed, but instead I was more shocked that it worked so well and there was a spot I had been overlooking. It was a weird one, where you kind of dig into the tendon, and I was left thinking about it for the rest of the day, like what the hell did she do to me? It really helped fill in some gaps for me about why some spots are ticklish in a certain way (joints and tendons).
These days, when being a lee, I find that I continue to build my intuition and technique through experiencing it, especially since the people tickling me are also tickle obsessed!
Did you have a single "ah-ha!" moment with the stomach spasms one that you can remember, or was that just a gradual process?