According to this lovely Schick advertisement from 1958, the biggest shaving nuisances are having to touch the blade, having to take apart your razor, wasting time and irritated skin.

I can see the last one being a pain in the posterior, but the other three? Might be marketing desperately coming up with ways the injector outperforms the double edge, might be thin skinned shavers.

A couple of other take-aways; allegedly you can shave faster with an injector than any other razor – other ads from the period suggest up to five times as fast, but I would like to see the data supporting that assessment – and a brand new Schick with twenty blades costed the equivalent of eleven and a quarter US dollar.

As a sidenote the picture in the advertisement clearly shows a late G-type razor, a style that as far as I can find went out of production three years before the ad was printed. Reuse of existing graphical elements, or selling of the last of the old stock?