Out of 30 cows we get 0-2 calves a year out of the clean up bull. We AI for 70 days, we ultrasound half way through and then again 5 days before we turn the bull out. That way if somebody is open that should be AI'd we can Lute them and AI one last time, and we will do some fetal sexing at that time. I really like the ultrasound, our vet can pick up cysts or infections or any other problems and we can manage accordingly.
A note about palpation and abortions. Our vet has never been more than 2 days off on ultrasound dates. 3 years ago we had a cow 35 days pregnant that he called 28 days. He said that there was no way that it was a 35 day pregnancy, and although the heart was still beating, it probably stopped growing and was in the process of dieing. 7 days later the cow was in heat. If we would have palpated that cow, I would have blamed the vet for rubbing one out, when it was just mother nature. BTW she concieved and calved to that heat she had 7 days later.