With a mild razor, a sharp blade usually works best. Try a Feather or similar.
The Tech has a narrow effective angle. Outside of that angle, whiskers don't get fully cut. This is why people complain the Tech is too mild. You do not have to "ride the cap". Aim for a more neutral angle. To find it, listen to the whiskers being cut and stay in the middle of that zone where you will get the closest shave.
Right, and also, back then the Techs were made, usually a person only owned one razor, and they used it every time they shaved. They also used the same brand of blade very time as well...the local drugstore probably only carried three or maybe four choices.
Anyway, using the same gear every time meant that not matter what it is, people got used to it and learned the best approaches, and it worked.