When we had only two hens we got two eggs each day. So when we got two more hens we naively assumed we'd get four eggs each day, after a settling-in period.
But our two older girls are hybrid layers. They're bred to produce an egg a day. The new girls are Rhode Island Reds, and there are some differences we didn't expect. Rhodies are utility birds, bred for meat and eggs. They're not as good at producing eggs as hens bred to be layers, and they're not as good at producing meat as birds bred for that purpose. But they're a practical compromise for homesteaders and smallholders.
Pure bred birds also go broody more readily than hybrids, as we've already found. So a four-egg day is a special occasion rather than a daily event.