I disagree. I have seen groves mixed in alternate rows with pine trees and the trees look far healthier than open sun and open air trees. My own experience so far mirrors this. They are an understory tree in nature and prefer dappled light. Every grove I see on the regular in full sun looks like hell. Could be they all have greening, but doesnt explain why the partially shaded ones look so much better. Partially shaded doesnt mean they arent getting 6-8 hours of sun, it just means they arent getting the sun full blast from 6am-830pm(during the summer)
It's conceivable that both are correct.
Mixed rows could yield citrus trees that are more productive in terms of product per tree, but less productive in terms of product per acre, because a non-mixed grove has twice the citrus density. Even if mixed rows yields citrus that are 50% more healthy/productive, 2x1 > 1x1.5.