Hello and welcome to the forum. I have found that feeding guidelines need to be tweaked depending on the dog.
Having fed both guru and gentle in the past, I would say their guidelines were pretty accurate for my dog. I am not sure why the other are so different. Maybe the moisture content is a factor but I would have thought this was pretty consistent in cold pressed foods. The best way to gauge is to keep a close eye on body shape. See feeding guide
It can be hard to assess genuine hunger in dogs as many just like to eat. My dog will always be looking for food but if I have changed foods in the past and she has been truly hungry, she has started eating earth and other things she wouldn't normally eat so I have upped portions a little or added more cooked veg or cooked oats to bulk it out.