After leash reactivity class we try to always ask "Which part was the best and which part was the hardest?"
It's very, very interesting how most people will then tell the best part.. and the "worst" part.
Part of that probably is that "worst" is considered to be the opposite of "best"....and so it just comes out. It also just seems like a very human thing to do... to perceive the question as where the errors/mistakes/fault could be.
The difference in the questions is very important. The "worst" part (not responding to a cue, barking, getting stiff when another dog barks, etc) is not always the "hardest" part (-when- another dog barked, -when- we got really far from the opening, -when- we were turning away). "Hardest part" tends to be something about the handler's choices or the environment. "Worst" parts are typically about incorrect or poor responses...and while we definitely have to consider these.... it's the environment and handler that we can change. And to change the environment and handler, we have to know what parts were harder and what components led to making things too hard for the dog.
I try to ask the "best and hardest" questions after all of my own training sessions. Griffin has been really great for the last few days. But a few of his behaviors hinted they could be weaker than I thought. He didn't make errors, he met criteria, and I couldn't even say how the behavior was different. Something wasn't quite how it should be....and I make a note of these weaker areas so that I can address them separately.