How long should you use a razor blade before changing it?

Once a week. I shave every day, even on the weekends, with rare exceptions. Usually I change the blade on Saturday, for some reason. If I’ve gone a day (or two!) without shaving, I’ll only shave with a new blade. My beard is rather thick and tough.

Yup. I do that too. (When I’m not sporting the winter beard)Five days a week I use either the Mach 3 or the Sensor Excel, whichever blades were most easily accessible (I refuse to track down a store clerk to unlock a shoplifting proof case for some razor blades). I get about 20 shaves out of each blade. Only rarely does the blade get so dull as to be uncomfortable before that.

You gents who switch every week or less must own stock in Gillette!

Perhas this should be a new thread.
1 cutting edge disposables are intended for one time use. It maximizes the manufacturers profit.
2 cutting edges improve the shave.
3 cutting edges are just about the point of diminishing returns.
4 cutting edges overkill?

I use a body lotion or face lotiion instead of shaving cream, stay in the steam room at the health club for 10-15 minutes. Stretch the skin with one hand and press the razor head into the skin and move the razor along a path perpendicular to the cutting edge(s).
It is side slip or a slicing motion that draws blood.