I think the poster asked when PVCs are considered frequent, not what PVCs are...
I'm not sure but I think 10% of your total heartbeats being PVCs and above are considered frequent, that's roughly around 10,000 daily depending, for those that feel everyone 10 daily probably seems frequent.
It is a diagnosis made when a surface EKG ( electrocardiogram) shows premature ventricular contractions, that is contractions which arise in the ventricles before the impulse from the atria reaches the ventricles. Hence they are early, compared to normal impulses.