whelping is NOT a precise thing! They are not machines and many bitches have their own timing. Many of mine deliver on day 59. Sometimes it can vary because of the size of the litter. It's more like getting to know your bitch's individual whelping habits. After all, human women have their own timing also!!!
Sorry I don't agree. Just try and tell the human mamas that when they are early or late in delivery. There are MANY factors that can and do effect the whelp date, including the individual bitch and the size of the litter.
My dogs are bred the day the bitch is willing and then for the next 3-4 days. So, there is no way they are bred "late". The "flavor" of your post seems too absorbed in a "preciseness" that's not always there.