I first started shaving in the late fifties – early sixties and I used double edge carbon steel blades that rusted out before they wore out. A few years later Wilkinson Sword came out with stainless steel blades and Gillette soon followed. Both fixed the rust problem but they seemed to wear out just as quickly as the carbon steel blades and were relatively dangerous to handle without cutting myself, either from nicks while shaving or while changing out the blades.
Double edge razors were soon followed by single edge blades, which were safer to handle, and usually resulted in a better shave.
Technology soon gave us the disposable cartridge with a single blade enclosed in plastic to reduce cuts. Soon the race began to provide us with multiple blade disposable cartridges. I guess the premise was that what one blade can do, two blades can do even better. Gillette led the way with the Trac II and Schick and others followed with their proprietary name.
Gillette then upped the ante and came out with the Mach3 with three blades and not to be outdone the other manufacturers quickly followed their lead.
I am not sure but I think Schick was the first to come out with a four-blade cartridge, called the Quattro. Gillette, not taking this sitting down, came out with the Fusion, a five-blade cartridge
Keep in mind that with every technology improvement there was a hefty price increase.
Thank God I have a full beard and mustache, otherwise I would not be able to afford to shave.
Now, I think the time has come for someone, Gillette or Schick to come out with the Octo-blade shaving system – yes, a cartridge with eight blades. Forget going to six or even seven blades – they should immediately go to eight.
They could even get Octomom, Nadya Suleman, to do their commercials – that way she would have a steady income stream so she could keep up with her mortgage payments so she will not go into foreclosure.