As can be seen in the preceding photographs, our chicks have quite a disparity in both age and size. In the second picture for example, the little Orpington is almost the exact same size as the head and neck of the sex-link to her immediate left.
The first batch of sex-links came in on March 3rd, the second group which included the Black Australorps arrived on March 9th, while the little Buff Orpingtons and Silver Laced Wyandottes, were added on the 16th. While there are plenty of sham fights and posturing to establish the pecking order, the smallest chicks seem to be ignored as they don't pose a threat to the larger birds.
While there is always an element of luck involved, I suspect having a 4X8 brooder (each chick has a square foot plus) may be a factor in our success over the years.