10 minutes is overkilll. Once it comes to a boil, the chances of anything harmful surviving is very low, if not impossible.
I harvest 1 qt wort pre boil, never checked the gravity. Yeast starts. Myth? Probably. Unless you are following German Purity laws, brewing is up to interpretation, and what works for John Palmer is not gospel.
Interesting to hear others thoughts on JP. I actually thought he'd adapted pretty well to the times in his latest addition of How to Brew. Good luck man! You'll make beer!
I have been doing my staters wrong. For years. Heard 1/2 cup to 1/2 quart repeated several times and memorized it. Easy to fix though. Thanks for posting.