Another thing is to get really good quality belts. The best I have found that are readily available are the Gates green stripe ones, which are also available NAPA branded. They have a bright green coating that makes them distinctive. I get years out of one of these driving a 100-amp alternator
. I've never actually snapped one, but I replace them when they show visible signs of wear. Still get some residue, but that is usually from me neglecting to check the belt tension frequently.