It's a short article and worth a read. Some of the activities Kirshner suggests are similar to those Atul Gawande makes in the appendix of his book Better: A Surgeon's Notes on Performance.
Related to this theme is a New Yorker article by Gawande, Personal Best, on the advantages of challenges of engaging someone to coach you in your profession. I continue to be amazed at how much I'm learning from Gawande, a surgeon, about how to be a better software engineer. I suspect that I first realized this when I started learning about Patterns. (The short post, The Pattern Technology of Christopher Alexander by Michael Mehaffy and Nikos Salingaros discusses how an architect influences the software development community.)
Maybe the common theme of all these writings is that it's important to be ready to learn, and you can learn from the people you least expect to.