I'm just barely getting into DE shaving for my head, and one thing that perplexes me is the lifespan of a single DE blade. Whenever someone gives their opinion on how many shaves a specific blade gets you, they always say something like "3-4 uses". No one ever seems to address the fact that there are 2 edges on each blade. When people say a blade can be used "3-4 times", do they mean per edge of the blade, or just in general?
And if it is per edge, how do you guys keep track of which edge you're using? Do you pick which edge you're going to use for that shave, and then make an effort not to flip the razor over while you're shaving?
Or do you guys not keep track of shaves-per-side, and simply flip to the other side if you feel like you aren't getting a good shave?
I feel like I may be missing something because in every shaving tutorial I've ever watched, no one has mentioned anything about this, so apologies if this is a ridiculous question!