As an interviewer, candidates occasionally ask me "How did I do? Where could I improve?" when I ask them "Do you have any questions for me?" at the end of the interview.

I usually say (and I happen to be in a country that is not very litigious) "While I can't tell you how you did in this interview -- we have to go through HR's process first -- I could offer you some general advice based on my experience", and would give some positive suggestions based on what I've observed. E.g. "try to read up more on how technology X works under the hood" or "when faced with a complex problem, it's okay to take time to think it through or ask questions", or "your communication skills are good, but you can be even better if you lead with the answer and have the lengthy explanation follow the answer" etc.

I'm wondering whether this is a good practice?