^^Like your quote, "but I know where to get it"

You can simmer as long as you want, 10 minutes has always worked for me, I suppose if you weren't using finely ground ganja, it would take longer to reach all the trichomes. By all means, go as long as you wish, I can't quote anything specific, but I do know that trichomes and THC are temperature sensitive. If you get it too hot, you start destorying THC, eventually leaving you with funky butter.