No, I'm not talking about the hair on your legs, or pits. I'm talking about shaving the skin off your feet. We have callouses on our feet for a reason. We walk on our feet. Our skin is supposed to be thicker there. Otherwise we wouldn't be able to walk, let alone run. (Not that I do that...) As a nail tech, I see all kinds of different feet, and I know that no two feet have the same callous. Some people have althlete's foot, some just have callous that starts to peel away. (By the way, you don't want to peel skin off your feet...just trim it off. Trust me.)
I can confidently say that using a credo blade (also called a callous shaver) is illegal for salon use in Massachusettes and Iowa. They are not the only states. You can call a beauty school in your state and ask to speak with the nail instructor. They will know for sure if it is illegal in your state or not. If it's illegal for use in a state, salons can receive fines for using them.
Why is it not good to shave your callouses off? Well, putting the risk of slicing the bottom of your foot aside, you are simply taking off too much skin too fast. It is better (and safer!) to use a foot file. The best one I would recommend is the Swedish Fot File made by Flowery. This is the holy grail of foot files in my professional opinion. They are disinfectable, sturdy, and the grit lasts and lasts. These files are not cheap, they are usually around $10, but are well worth it. After using them, you can scrub them clean with soap and a scrub brush. Or, of course, see a nail professional who would love to do the work for you! :)
Another thing you don't want to use, is those round devices resembling an egg with a cheese grater. Yes, I know what they are called, but am not saying it. You know what I mean. This is like a ton of razors scraping away your skin. Your skin is getting cut away, chunk by chunk, unevenly. This is why I still recommend a professional foot file. Cheese graters are meant for cheese. Not feet. Even if your feet smell like cheese. lol
So please, just say no to shaving.