The feed is generally accepted to be enough calcium to support a laying hen's need.
Now, you may still get odd eggs, like no shells, or weak shells, or weird lumps/bumps/ridges on the shells. I believe these are glitches in production in the hen's system, not related to calcium intake. New layers have an abundant store of calcium to draw from yet still lay these funky eggs from time to time. As long as it's once in a while, it's not to worry.
I don't feed layer feed, I feed an all-in-one as I have various ages and both genders. I keep all my egg shells and toss them back in the run. The roosters don't eat them, the non-laying pullets don't eat them, the younger hens might peck at them but my older layers gobble them right up!