Can of worms. some would say that was normal – but I would say not. No conditions I have ridden in do I get less than 500 miles out of pads and usually thousands.
How many miles is that?
some would say that the peaks are very harsh on pads – but others seem to get good life even in the peaks
There seem to be many factors at work – not just the soil conditions but riding style, type of brakes ( but hopes are usually good) speeds etc.
I think the crucial factor is getting the brakes hot enough to be in their efficient working zone. Do you have big rotors? My theory is big rotors may not get hot enough so the brakes run in abrasive friction not adherent friction thus resulting in the high wear rates. My logic for this is that on the tandem where the brakes run right on their limit of heat capacity the pads last forever.
However this is all very debatable