I haven’t had the opportunity to practice shifts much at autocross, it hasn’t been needed (much). The 3->2 shift is the most awkward one. When I’ve been driving on track with the MINIs, there are a few places where I do need a 3->2 shift (like turns 11 at Laguna and Sonoma), but there there’s a straight leading up to it, to give you time to get your act together, and I’ve done it so many times I know exactly where I need to shift.
Shifting in autocross is much different, there’s no time to think and I have to get the right shift pattern within a few runs. Without much practice at it, I was a bit lost there. I was trying to work out a shift pattern looking at the data on the lap timer, but I got it wrong. A shift somewhere along the long side, and on the final “straight” (negative offset slalom) would probably have worked, so I’d need to have shifted down going into the final sweeper.