Many things can affect the life of the front pump seal.... dusty or muddy operating conditions, manufacturing anomallys, excessive heat, moisture (especially in conjunction with freezing temps.), excessive runout or imbalance and even any number of problems affecting the clearance between the torque convertor and the bushing. A plugged breather (this is not an overflow, BTW) can have a deciding effect as well.
Mileage, climate and vehicle use play a distinct role in the life of most any part and, especially, those parts considered "sacrificial". When you ask a question, pertinent information can go a long way to assisting in a meaningful diagnosis.
