Spaugh, the guidelines for the low biuret urea spray program is indeed heavily followed throughout California's citrus growers. In fact, the guidelines that are posted in this thread are for California growers, and are published by the University of California Agriculture & Natural Resources in their publication "The Citrus Production Manual". No matter how good of a crop your tree produces, following the Citrus Production Manual's guidelines, your tree will produce a larger crop, and more importantly, a crop with a larger and better quality fruit.
Yorgos, night time spraying is the second best time to spray, whether its spraying for this program, or general foliar spraying. The absolute best time to foliar spray a citrus tree is in the early morning on a cloudy humid day.