It depends on where you live from my experience. We use to live in Kansas where the humidity is really high and never covered any holes in the deli cup. We now live in southern Oregon where the humidity is really low and cover all holes in the deli cups. We've had no bad eggs do to molding or drying out. Hope this helps.
Hey "NoDavid"...."NoHoles" if using Perlite...........
Perlite is a drainage material.....allows the water to go to the bottom. Thay why it will look dry. But with "noholes" the humidity will handle the eggs nicely.(if they are fertile).............other than perlite being used...other methods
exist...........take "nocare" "noHJ"