Today is a Mach day, my 10th 3-pass shave using the same fusion-pro-super-glide-whatever 5-blade cartridge. And once again an awesome smooth irritation free shave, DFS with only slight alum sting, very slight if any. I have to hand it to them, the thing is performing way better then I had expected. At least for me arguments of price or quality are getting harder and harder to justify. Even if the cartridge expired now it would factor down to $30 / 8 / 10 = $.38 per shave x 180 = $67 per year for me to get 3-pass DFS or better shaves.

Having said that I think the principle reason it is lasting so long is in the proper wet-shave prep, products, and the added stretching skills learned through straight razor shaving. In fact from a time argument shaving by cartridge in this way takes every bit as long as with a straight, there is no savings there assuming the same prep and passes, as well there is no saving in product. What I have found that is being saved however is (besides the fact that scarring yourself is very unlikely) the excitement factor and feeling of tradition is what is lacking.