Brake Pads Wear Fast

98 Chevy Cav, 130k miles, 2.2L

I have changed the brake pads 3 times in the last 3 months, roters twice and the calipers the last time. I can not figure out why they are wearing so fast. I don't feel the calipers sticking.

The only variables that changed was I started a paper route about 4 months ago, so I hit the brakes a lot. I also put on a different Lifetime Warranty brand from AutoZone. I don't think these should effect it that dramatically, but any other ideas? The pads need changed again for a fourth time. Thanks.