I get 4 good shaves on a good blade using my DE. A fresh blade per shave would be best for me, but I'd rather save the money.

However, when I used a shavette, I noticed that my shaves improved--and I didn't cut myself much--when I kept using the same (1/2) blade through the week. A new blade per shave ended up chopping up my face. I switched from the shavette to a SR a couple of months ago, so I don't have that issue any more.