I can't speak for anyone else except myself and my own egg collection. I collect eggs for several days during the week, package them on Sunday afternoon and mail them out on Monday morning, usually by 9 a.m. Almost always, they arrive within two days, sometimes three. I don't know how soon they are set in the bators after they get where they're going, of course, unless they tell me.
I think egg storage of even up to two weeks shouldn't wipe out any significant percentage of a setting of eggs. I realize one week is optimal, but in reality, eggs stored properly up to two weeks should hatch, all other factors being satisfactory. We are dealing with so many other more likely factors than the storage here, I think. And it can be a combination of things, too, so perhaps difficult to pinpoint the exact cause.