I used that technique too when shipping eggs. I am probably not going to do that any more though, cause it is rather faulty in my opinionSome of the eggs that were sent are older - The breeder mentioned that right off, that they were as much as a couple weeks old. So we'll see how they are for viability. I think that's part of why she sent me so many - to see how well they're holding viability. She did something I haven't seen with any other eggs I ordered.. which, realistically, is just two batches of Serama eggs. She bubble-wrapped them individually, had them inside one box laying down - not in cartons, not upright - with layers of bubble wrap, and aluminum foil lining the box. Then that box inside a larger box, with bubble wrap padding on all sides.
A few of the air pockets are a bit saddled, but to my surprise, not very many. And none were completely broken loose.