I love this! This isn't about some ratio of good to bad. It's about engaging with the individual and encouraging more of what you want to see. Telling someone something is bad is helpful-ish. Telling someone the parts that are great -- that you want to see replicated again or extended in the future -- that's useful. And rewarding to everyone involved.

It's really only useful to give negative feedback if it's something that SHOULD NOT happen. Otherwise, learning to accept people where they are in life goes a long way.