Hello and welcome to BYC!
Egg binding happens for a few reasons and most of them can be prevented.
Dehydration is a common cause...should they run out of water for a long period of time. The oviduct becomes dry and the eggs stick.
Not enough calcium...the shell needs to be nice and hard for it to properly travel from the Uterus out the the vent. If the shell is soft or broken, it can stick.
Calcium is also needed for the hens contractions to push that egg down the Oviduct. Without sufficient calcium, she can't push as well.
Egg binding can be genetic too....her momma became egg bound a lot. Very large eggs can get stuck, along with laying too many eggs in one day. (yes they can lay more than one egg in a 24 hour period. Not all that common, but it does happen) Young early layers can be susceptible if they don't have sufficient calcium or their bodies are not ready for laying. Some of the production breeds that lay early and hard can susceptible to egg binding. And of course with egg binding can come prolapse...when she pushes so hard her insides comes out.
So it is best to keep them in water at all times, keep oystershell on the side for those that need extra calcium, don't over do the protein so they are releasing more than one yolk at a time, get young pullets on layer feed when they are close to laying, keep them healthy so they put on a hard shell, and if one starts to lay thin shelled eggs, you can add some human Caltrate at the rate of a 1/2 pill daily for a week or so until they are topped off with enough calcium.