So if an Aids couple hooked up and decided to be monogomous, then protection should not be an issue, unless there are two different strains. Of course monogomous is probably an oxymoron, as it requires predicting human behavior, which usually does not measure up.
More married couples should probably be using protection for the same reason.
I used to enjoy pizza that had been in the refrigerator a few hours or a few days. Pizza has never lasted long enough in my household for me to get a good vision of the pizza you are referring to. But I get the idea of what you mean.