You'll get a whole lot of different answers because there are a whole lot of different things that work. We all have different incubators with differnt numbers of vent plugs, some are forced air and some are still air. Even our average atmospheric pressure is different depending in whether we are at sea level or on a mountain top and that can affect how much moisture the eggs lose during incubation. At different times of the year, my relative humidity in my house can vary quite a bit. I think the higher your elevation, the higher your humidity should be because of atmospheric pressure, but that is just me thinking, not anything from actual experience. I also think with a forced air you need a little higher humidity than with a still air since the moving air should dry things out a little easier. Maybe not so much during incubation, but especially during hatch. But again, that is mainly me thinking, not based on actual experience.
Enough with the theory. That is not what you asked. When I first got my 1588, the instructions said to fill the center water reservoir and go with that during incubation. I did and it worked pretty well. Sometimes that gives me around 42% humidity and sometimes around 50%. I mainly use my hygrometer to tell me when that reservoir is dry instead of worrying about exact humidity. I can't tell a whole lot of difference in my hatches with either humidity.
During lockdown, I get the humidity up to around 65% to 70%, though the humidity goes up to maybe 85% when they start hatching.
I'm not saying mine is right or wrong. It is just what I do. I suggest you be fairly consistent with whatever you do and see what results you get. That way you will know what to change for the next time, if you decide to change aything. If you are not consistent through the hatch, what will you adjust next time?