I used to keep a few razors loaded up with a blade. Then I started moving the blade around from razor to razor. For the past year or so, I don't bother. I keep the same blade in one razor and use that combo for several shaves. When I'm ready for a change, I don't worry that I may still have some use out of the blade since even expensive DE blades are pretty darned cheap and I have enough of my favorites for a couple years of shaving at the moment (and can easily buy more). I also don't worry that this means that I may be slow getting to some razors. While I have 16 razors, I have 4 or 5 favorites that get 90% of the use no matter how I do things so it really doesn't matter.