There are all kinds of methods of dealing with the exposure variations due to filtration, many dependent on the producer of the products involved. I have not seen any universal method of compensation that work well yet. I always have had to make strip tests.
There is another issue here. As the contrast changes, the overall exposure usually has to be “corrected” because every “zone” will be rendered differently. This may be the primary reason no one has been able to produce the
”universal correction” chart or formulae (equations). I love this stuff ;-)
"I love the smell of fixer in the morning. It smells like - creativity!"