I see on sites like Blichmann and others that a brewpot is recommended to be 1.5x the size of the boil. Why is that? Is that just to minimize boil-over? Or is there a hop utilization dealy-o? I usually boil 11.5 g in my 12 g pot and have no problems with boil-over. Of course, I watch the pot like a hawk and stand ready on the regulator with a spray bottle. But I've had exactly one boil-over in over 20 batches brewed. So why the much bigger pot recommendation?