Well...here's another reason why you NEED more than one razor.
How in the world are you ever going to do a Presidential Shave with only one razor?
One pass, one razor. OR, one cheek, one razor. That's just silly amounts of fun.
Seriously, you could probably get away with one razor for all of eternity, but I prefer to rotate everything. Razors, brushes, soaps, strops, aftershaves and colognes.
It also allows me to be completely truthful when I say to SWMBO "I can't get rid of anything, because I use ALL of it".
Have fun.