I think the reason we get so many different answers is because everyone's situations are different. I think we have to take into consideration our climate, temp., outside and inside humidity, type of incubator and whether or not they are still air or not. I don't know that all these things are actually factors, but I'm learning and believe that what works for me, may NOT work for you.
According to the "how to" pages, "You want 50% humidity for day 1-18, then 70-80% for the last few days". I had read elsewhere that the humidity during hatching should be between 60-65%. This is NOT working for me and I'm having too many chicks struggling or dying trying to hatch with dry membranes. I have chicks due to hatch in 4 days. My humidity will be between 70-80% this time.
Hope this helps!
Did 70-80 work for you better than 65