two and a half hours since post...just curious? For us, if a heifer is not getting down to business 45 minutes after the bag bursts...this means no progess of a foot or two, no desire to push...we check. If all is well we will leave her for another 1/2 hour to 45 minutes. We err on the side of caution when they just do not want to settle down and no progress is made. Sometimes it's just a gut feeling. You know, the way a cow looks, and acts, that says "I got me a problem, alittle help over here!"
Then there are some we do leave a little longer. It all depends on the situation and what is going on. Each time is different.
The other reason why we are a little inclined to check, but not pull, a little early is our distance to the vet. If there is a problem, by the time the trailer is hooked up, cow loaded, taken to the vet 1.5 hours could have elapsed. That is much needed time to save a calf if the problem ever arose. If the vet makes the house call, it could be 2 or 3 hours before she arrives. Which because it's a busy time of the year, calving and all, she prefers that the farmers bring the cow in, then it cuts her travel time and it allows her to help more farmers in a day.