7-10 days is generally the max "shelf life" of eggs. When I collect eggs to ship I only like to send what I can collect in 2 days time. So if I ship to someone on Monday, I send them Saturday & Sunday's eggs, plus whatever I can get on Monday morning before I ship. I'll usually include Friday's eggs as extras, but I generally won't sell eggs more than 2 days old, as they are then going to be in the Postal system for 2-3 days. This means that the eggs are going to be 3-6 days old when they get to the person buying them. If I shipped eggs any older than 2-3 days old, the buyer would be getting unacceptably old eggs, in my opinion.
That said, I've had eggs that were in the Postal system far too long develop nicely. Right now I have 8 eggs in my incubator that traveled literally coast to coast and were in the Postal system for 5 cold days before they were delivered to me (in the middle of the biggest snowstorm our area has seen in 10 years, no less
). I haven't done a good candling/count of all of them yet, but I took a peek at several on day 4 and every one I looked at was developing!! (Equibling, these are your Orp eggs!! I'm impressed--these are tough babies!) So I can assume that these eggs were 6-7 days old when they got to me, and they are doing great! So sometimes they do defy the odds.
Of course, these particular eggs were older than they should be because they got held up by the P.O., which is no one's fault of course. You gamble anytime you ship eggs, no doubt about it.