Irregular eggs are normal. It is a trade mark of each hen. Soft shells are a sign of poor calcium absorption.We all know this. I hit on this with a couple of sick chicks (be nice) that I treated with electrolytes, mash and heat.While looking for help I found a recipe, I wish I could find it again, for home made electrolyte drink for hot weather. I used store bought. The chicks didn't make it after a rebound but the rest of the electrolytes went to the flock on a hot day. They drank ALL of it. What eggs we had the next day! Huge, hard shelled, and grade AA, with dark yellow yokes. In all of my searching I found that baking soda helps aid in calcium absorption. I gave it to a sheep with heartburn and my hens went crazy over it. How much you ask right? I don't know for sure but it seem they know. Free range REALLY requires more grit (you'd think they could get their own without visiting the road). BTW I had a 5 year old hen who still laid nice eggs, small but nice.