How long do razor blades for boys last at most?

Depends on the type of blade, but also depends on the area of forest cover and frequency of logging.

Imported blades (the traditional blade holder type) are relatively longer lasting and may be made of better materials, such as Gili blades. It is estimated that the use of a few months is not a big problem.

Electric razor head life is longer, I bought 3 years ago Philips electric shaver has not yet changed the head, still sharp. I shave every day, rain or shine.