All I can tell you about what people do with solder paste at the end of the day or for the weekend is.
What the manufacturer recommends. What people say in public? What companies actually do as far as reusing it?
I am not passing judgment on 1 or 3 it depends on a lot of things and the type of products you are running. If you are making Blinking LED novelty buttons reusing paste, maybe no big deal. Making aircraft electronics, maybe a big deal. Most companies I have seen are all over the place on their reuse policy’s if they even have one.