That is expecting a lot out of a single belt to drive that compressor. I would not expect a long belt life. I would also hope the pulleys involved with that single belt drive are in very good condition and can also be easily replaced. Continued belt slippage also wears on the pulley groves because the belts drive off the sides of the "V". When the belt reaches the bottom of the "V" the belt no longer drives anything, it just slips.