Personally, for me, I wouldn't allow myself more than one every couple of days. Not because it might push me over my calories but just because I want to get out of the habit of having things like that. I don't really want to snack and if I'm going to, I want fruit etc. instead so it's more healthy. But then that's me, I know that I'm trying to remove these things and introduce them as an occasional treat so having one or more a day wouldn't really fit with my aim. So I guess you have to ask yourself, what is it you're trying to do? Do you just want to lose weight? Or is your attitude/relationship with certain foods not too great and needs fixing so you need to eliminate them and use them as a treat every so often? I think it's something completely individual so no-one can really answer it for you!