Everyone gets so wrapped up in 'hatch rate'. Hatch rate means nothing, if all things are equal, meaning that the incubator is stable, holds temp and humidity, your still not going to hatch many eggs if the fertility is low or non-existent.
Shipping does effect the eggs but sometimes I've had 100% hatch from shipped eggs, (7 days or older) others that I got locally, (under 3 days old) I had 10 to 0% hatch. So it does matter if they are fertile.
With any incubation, you will have a certain % that stop developing early, mid way through and late (dis) or will pip then die or die soon after hatching....some people count those that hatched but died in their hatch rate, so that's not an accurate hatch rate....was it fertile, yes but not indicative of a high hatch rate.
Alot of suppliers of hatching eggs will ship eggs they know are not fertile or old eggs, and misshapen eggs but they advertise they have high hatch rates....that's the 'catch line'. If you have been hatching eggs for anytime at all, you will know that hatch rates will vary from person to person due to the various methods of incubation that are used and the experince and knowledge each one has with the incubation process.
Button eggs appear to ship better than larger eggs. I've always had good results with them but I have noticed that buttons have better fertility then other birds.
Good Luck with our hatch!