Getting 12 eggs a day but only 11 hens?

Just as the title says, we’ve got 11 hens but we usually get 11-12 a day. Sometimes 9 or ten but that’s not as often as 11-12. We looked it up and it said they’re supposed to lay 3-4 times a week? They’re about 8 months old (got them in August) and started laying in mid-late February. (Picture of some of our newest little ones)