You only need 2 to 3 nests for 10 hens. Actually they are doing well to use 3. I have 9 hens who use one, sometimes two, which is a very common experience. One theory is they lay where others did because it makes it a good spot to lay -- another, that maybe someone will hatch their eggs for them.
You will want to stop their using the nest or its edge for a roost, as this will get your eggs poopy. Roosts need to be higher than nests, as they like to sleep as high as they can. You may need to start closing off the nests at night so they can't sleep in them. They won't lay at night. I use empty gallon milk jugs to do this as it makes it easy. Of course you have to remove them in the morning
Excellent advise.. i have two levels of roosts above the nesting aeras but i have seen one on the nest and one perching on the nest entrance. the mike jugs sound like a great idea..