Yeah, for me that one day rule is more like weeks or months. If it's the "first" thing I use, I usually have no problem with the initial learning. Like, I had no problems with shifting on my first bike with trigger shifters, or even my first road bike with STI shifters (other than wanting those little numbers to tell me what gear I was in. I got over that). I had no issues learning to use clipless pedals, either.
But, if I have to change using a mechanical thing after years, or go back and forth between systems, it's really hard for me. Once a pattern gets in my brain, that's it. I clip out with my left foot. I absolutely cannot clip out with my right. I've tried, but, I just can't lean my bike to the right. When I first started riding I did clip out on the right, I switched for some reason, but I should have kept using both and that would have been fine. I was worried about the compact double on my new bike, and going back and forth between that and the triple on my Kuota, but it's fine. What is a problem is that the bikes feel so different, I feel horrible on the new bike. Not horrible that it doesn't fit; it's a custom bike and it probably fits better than my Kuota. I feel weird because it has different geometry, which makes me cautious and slow. DH really wanted SRAM on these bikes, but I said no way for me. Too many changes is overload for me.
2015 Trek Silque SSL
Specialized Oura
2011 Guru Praemio
Specialized Oura
2017 Specialized Ariel Sport