Sir Isaac will tell you that the amount of brake material used over time is a measure of the energy being absorbed/dissipated. It costs brake material to pull kinetic energy from the 2-wheel system when the brakes are used. And energy is a strong function of the system mass (weight essentially) and the square of the velocity being scrubbed (E = 0.5*mass*velocity*velocity). So if you carry more weight, you eat more brake to stop, all other things equal. If you like to stop from a faster speed, you get a squared effect in brake material loss, all other things equal. If you're fast AND heavy, well, you get the picture.
The front brakes have more pad surface area in contact with rotors so they should wear less quickly (as measured in pad thickness) because they can spread the workload between both disks. As a rough estimate, the same amount of material would be used to stop the machine, front or back. It's just that the front has more to give up so it might seem to wear more slowly.
Aggressive riders will tend to go through pads more quickly because they put more energy through the system and do so at a quicker pace (more power generated and expended). That's why a tracked car would use its brakes up far more quickly than on the road, all other things equal. Racing machines eat brake material.
There are ways to get the most from your pads/disks & other elements of your binder system. Use your engine for braking; downshift into the stop. Also, less hard-on, hard-off riding. Brake temperature, which is a measure of how much energy is being pumped into the brakes, can significantly affect the wear rate. Hot pads tend to wear more quickly, again, all other things equal. Better energy management which basically equates to getting through the same bit of road at the same rate with less time on the binders. This equates to driving skill really. Things like line selection, corner entry and exit, apex selection, etc. And finally, there's just going slower...less energy in the system means less brake work for the binders.
For those with a performance bent, brakes are probably the most important piece of the big picture after the tires. It is said by many who live on the podium that the center pedal wins races.
Cheers,
W2