I have had Serama/OEGB and Serama/d'Uccle bantams for a year. They started laying at 5 months and began pumping out eggs at what to me was an astonishing rate: each hen laid 6 and even sometimes 7 eggs a week! This continued until the flock all got fowl pox in the fall; when they started laying again we were into winter and production dropped off but I was still getting an egg or two from each one every week. Then this spring it was back up to an egg a day most days. I let all three go broody and hatch out clutches. Now they're back to laying and even with this extremely hot weather I'm getting 5-6 eggs a week from each of them. I don't know if this is typical of the breeds or not, though.
The eggs are small, of course, and the proportion of yolk to white is higher in such a small egg.