My policy for my customers has always been --
1 - failed twice to sync properly -- OUT
2 - failed twice to be accepted for transfer - OUT
3 - failed twice for pregnancy after transfer -- OUT
4- ANY combination of the above
If you get too set on using any one particular cow -- and she keeps having issues, you are ultimately losing out on your entire programs success. After all it takes to get to that point -- this is where you need to be ruthless or you are losing out --
I know it may be hard to replace a certain cow for the recip herd, but if you do not be really picky here -- it costs alot . I have had a few that would not sync correctly -- say they were off a day or so, and came back and used them later for frozen. If they didn't feel good THAT day however -- it's over. You just have to be ruthless here or it is all for nothing!
Best of luck --
Terry