I can remember very clearly the first time I experienced this phenomenon, albeit on a slightly lower scale. At the time, I was wearing around 9-10 cm pretty much all the time, and got to where I felt pretty good at that height. Then one day I wore those 7 cm sandals that I just got rid of, and I thought, "Man, I can really zoom around in these things!" I almost started running everywhere, because I could. I never much advanced beyond the 9-10 cm range until recently, thanks to this challenge. I don't want to say I can zoom around in 10 cm, but they feel much less like heels than they used to.