
This is a contentious issue, lots of things have to be taken into account when making the decision. I personally have withdrawn only once in the past to remain eligible for BIS. It was a non group system show, and 3 different people were judging the breed, the variety class, and BIS.I was lucky that day, obviously it doesn't always go according to plan. I informed the ring steward in advance, that I was withdrawing from the variety class in order to remain unbeaten.
At a Group system show, your puppy would have to be declared Best AVNSC Pastoral puppy, then Best Pastoral Puppy(ie, Group 1) prior to becoming eligible for BPIS. Neither of these steps can be skipped.So as you can see, there's not a simple answer to your question. It depends upon so many things. Some might say that you should compete in all the classes entered in the spirit of the fun we're supposed to be having. There's some truth in that, I have to agree.