Twigg, tell that to my brooder full of chicks. I have stacked eggs, and adjusted the temp down one degree to compensate for a few days, with great results. I would never try it for an entire hatch, but a few extra eggs for a few extra days, I have had good results. I have just hatched silkies along with Black Jersey Giant eggs, again, good hatch, I have hatched marans along with silkies, which are supposed to have different humidity needs. I just run 'em at 40% and the silkies did great, the marans less great, but they are my birds and I have a steady supply of eggs so I don't stress if they only hatch 70% or so... better than no chicks. I think a full bator is more stable than one with just one dozen silkie eggs in it. Hence I believe filling the bator, even with mismatched eggs would hatch better than a bator with only ten silkie eggs. To each his own, and I know and understand the theory you quoted, but my eggs must not have read your book. It probably also says not to put your eggs in the fridge, lol.