The mechanic said the brake are wearing unevenly and faster than usual
this tells me that you have issues with the calipers. if you have uneven wear as in one side of the rotor is worn more then the other (usually the outer surface, as the pistons are on the "inboard" side of the rotor, the inner pads are stationary where as the outer move in and out as the brake pedal is applied) then the calipers are sticking, either the calipers slides are worn or the pins are corroded and/or gummed up. if the brake pads are worn thinner at the bottom and thicker at the top of both the inner and outer, then bottom piston on the caliper is gummed up or corroded meaning the piston is not returning once brake pedal is released (would be same idea if the tops of each pad is worn more then the bottoms) I would look at replacing the calipers with rebuilds after all truck is over 11 yrs old, time to replace these parts.
