I've read references that selenium toner deepens blacks but also increases contrast. Does everybody print lighter and at a lower contrast grade when going to selenium toner? I've seen that people sometimes selenium tone prints days and even weeks after making them and that makes me wonder how they know what the final print will look like? It seems like the only way is to make a bunch of different prints at varying exposures and then toning and taking the best one, but that seems like a waste of paper and time and you'll always settle for a print that isn't as good as it could be.
Is there a certain formula for knowing how much lighter to print or how much lower your contrast grade should be when you know your going to tone in selenium, kind of like a dry down compensation?