TOO BIG?? NEVER! Can't imagine. My hubby just finished our last coop (LOL), 12x12. We have 18 hens and 2 roosters. It seems like I always want more chickens, bigger houses and bigger runs. Soo funny. Very addicting. I love my chickens.
According to the person who is designing it... no, it's never too big.
According to the person who is building it (or married to the person who is designing it)... yes, it's too big and too complicated!