I find the qualitative reflections most enlightening and especially that you said: "But never in the course of this experiment did I count something that turned out to be unimportant."

Your under-confidence in that point may be very common leading to thoughts like: "Yea noticing confusion is all nice but I usually do that already. I'm fairly certain that I'm only missing some irrelevant confusion." Your experience suggests that there is no such thing as irrelevant confusion. The art is to notice as many as humanly possible instead of just some.

I have never read a better motivation to go and actively try to notice confusion than this sentence. Thanks.