I have found that every incubator will behave a bit differently with humidity. Those with insufficient ventilation will get nasty fast with excessive humidity; those with excellent airflow and air exchange can get by with higher humidity without smelling like a bacteria laden wet sock. I've found that 45% is a good humidity in my GQF cabinet for incubation, and 65%-70% for hatching chickens and turkeys in both the GQF and in my Eco 20. Staggered hatches without good ventilation and with water wells under the hatching platform are exceptionally risky as the hatching debris will fall into and contaminate the water wells, raising the potential for navel infections after hatch. Excessive humidity in the incubator also produces stress in the lungs of the just hatched chicks. Too low a humidity makes it hard for the chicks to break free. The best thing you can do is to log every hatch and learn from it.