I don't have a policy, but as long as a parent has had a weekend at home of trying to potty train then I will keep going with it for the week and see how things stand at the end of the week. I don't require pull-ups, I actually prefer not to use them, but I have all hardwood and linoleum floors in my home so accidents are not usually a big deal to clean up.
I really believe that if a child is ready to train then that week is plenty of time. If not then I would suggest to the parents that we give it a break and try again in a few months. If a child was still having accidents at the end of the week and the parents insisted on continuing with potty training then I would go with the pull-ups.