I would probably adjust my original post to say you cant better without useful feedback.

I always ask for feedback after an interview, its almost always useless. And conflicting between company interviews.

Its pretty rare for me to totally bomb an interview to the point i don't know the question. Usually the situation is I answered the coding question, handled the follow ups, wrote working code and still get the feedback that the coding portion didn't go well. How do you use that feedback? Useless imo.