The behemoths of men's shaving supplies have done a fantastic job (and have spent a lot of money) convincing us that we need multi-blade cartridge razors to shave our faces. Let me tell you a secret...THEY ARE LYING TO YOU! But why? Why would they lie to us? The simple answer is....MONEY.
You see if they can convince us that we need these fancy multi-blade cartridge razors than they can charge us an arm and a leg to buy them. You can spend upwards of $25 for a 4 pack of cartridge razor blades. They even add "lubricating strips" to them to make the ridiculous price a little more palatable. Truth is a good shaving soap completely eliminates any need for some BS gimmick like a "lubricating strip". More on that later. Back to the blades.
So what does a multi-blade cartridge razor do to your face? Well, multi-blade cartridge razors pull/tug and cut the facial hair below the skin, causing damage and forcing some of your facial hair to grow inward. This creates bumps and irritation and completely ruins any chance of a good shave. You may just not notice it until the hair starts to grow back in. To illustrate our point see the below illustration.
Why is a single blade better? Well the single blade razor does the opposite. The blade is designed to cut the hair at skin level, causing the hair to grow back not under the skin but at the surface of the skin. Thus eliminating ingrown hairs and the problems that they cause. To illustrate out point see below illustration.