Well since I switched over from DE shaving to my Schick injector "model I" a few months ago I've been testing blade longevity. Reading the many posts on injector blade usage I tested my Schick blades for one a week and one every ten days. Then I just finished this April using two blades using one on the 1st and a second on the 15th. I'm happy to say the blades gave me a smooth and close shave. Granted I could see how long one blade last but I'll stop at two blades a month. So my routine is now a blade change on the 1st and 15th of every month.
With this type of usage I'm starting to get near the cost effectiveness of DE blades.
With this type of usage I'm starting to get near the cost effectiveness of DE blades.