Alley...fwiw.
I switched from starter to layer....(I don't have "grower' feed here) when I got my first egg.
I have
never bought oyster shell.
I have had only one shell less egg and that was in the first week of my girls starting to lay. Never had any other problems with anything regarding eggs...ever.
I don't even know what all flock is.
I believe that layer feed is what is it...what it was made for...a complete feed for laying hens and that is what I use it for.
I am willing to argue with anyone til I am blue in the face about the benefits of fermenting feed and feeding corn....but I don't.
There are many many people on this site that have been racing chickens for 30 plus years...which tells me they are old.

Older people (again

) are stuck in their ways and don't want to believe or listen to
anything anyone has to say.
I'll go back to my corner now..