In the early 1970s, people used single blade safety razors, and they had high standards. Now, razors come in a variety depending upon the number of blades they can house for effective shaving. It is said that a greater number of blades ensure no part of the hair is missed while shaving. However, when the beards are exposed to more than two blades, it may result in ingrown hair. Ingrown hair then grows up into bumps or even infections sometimes.