Especially as singers, we HAVE to think, as that’s the only way to affect our instrument. Questions I ask are: “What was the difference between that time and the time before?” “What are you going to do to try to change XX; How successful was what you tried and why?” “What did you think about that sound?” “What did you do differently?”
Overall, I have banned the words “good” and “bad” because neither tell you what to continue working with and what to try to fix. I also try to always use only positive directives. We’ll identify both what behavior we want to replace and then what we want to happen instead. Focus is then on what we WANT to happen, rather than what we don’t want.