I changed my system when version 1.28 came out. I'm now planning to beat eight AI2s before I start on AI3s, and each loss will cancel out three of those wins. (Previously, each loss would cancel one win, plus one win for each previous loss since the last time I went up a rank -- although dropping out of a rank and then returning to it would count.)

This change has made it easier for me to determine how much electrum I need to keep on hand in order to avoid having to drop down to AI1 prematurely -- in fact, it's a simple function of my "position" in the level, so I've put it into the chart I've been using to keep track of that position. It also seems like it'll practically eliminate the chance of dropping back to AI0: this will now require a win-rate of less than 75% against AI1, plus two more losses. (And it was already pretty low -- it's only happened twice so far, both times after fewer than three AI1 losses.)