Is it harmful to have too high a humidity in the early stages of incubating (up to 16 days) or even too little?? I know you need more humidity on hatching last three days or so.
In the early stages of hatching the eggs need to loose moisture. Yes the chicks can be hamed if the eggs do not properly loose the moisture. At the end the humidity is raised to keep the membrane from drying out. There are a few different approaches to early humidity. Some depends on the environment and the relative humidity. Most aim somewhere between 30 and 50% for before lockdown.