Edit: slightly tipsy, caveat emptor. I do stand by the message, might regret word choices later.
I dunno, after you learn how to shave with a single blade, you realize that your blades only cost between 10 and 50 cents each. That blade is good for at least 3, upwards of 6-10 shaves. (I've had several Feathers go 10, and they mostly go 8 for me...) Really good and comfortable shaves. The blades are cheap enough that if there's the least bit of tug or discomfort, you shit-can them.
I've tried stropping carts before. While it can extend their serviceable life, it's not comfortable or economic in my eyes (or against my face, if you will.) If you take some time to read about honing and straight razor maintenance, you'd realize that you can't sharpen a cartridge. If you can't "reach" both sides of the edge, you can't do anything but a half-ass strop job.
I don't mean to be aggressive in tone by way of word choice, but as much as it's "your mileage may vary," it's also irrefutable that you can't sharpen anything without touching both sides of the edge. I guess it depends on what you define as the outcome of just stropping one side of the cartridge's edge. Either way, life is too short to get bent out of shape about stuff like this. May all of you have comfortable shaves.