My Wyandottes, who are very good layers when they're not broody, go through a cup of oyster shell a week on average, even when they are on layer feed. There are many variables. No pet chickens here after my 1st batch 29 years ago.
Why do companies produce feeds like Feather Fixer & Kalmbach Full Plume & Feathering Feed & market them for molting birds? Maybe they know something we don't? Maybe feeding layer year round for years to molting birds, with some laying & some not, is not a problem? So is too much calcium for 4...