I have a very...VERY tough beard. For years I had to deal with bloody collars on my shirts because I couldn't find a good razor. Enter the Mach3. It was like a miracle for me. No irriation, no cuts. The Mach3 Turbo was even better. It's the only one I can use right now. If I have to buy a cheapie disposable for some reason I usually only get 2 shaves from it and then toss it because it will slaughter me if I try any more than that. Yes, cramming more and more blades onto a razor gets to be ridiculous, but for people like me they do help.
For anyone interested, here's a site that sells cryo-frozen blades that last a lot longer than store bought, for comparable price. I've gotten double the shaves out of them, which is a great savings, IMO.