I would not dare to build a course without fairway irrigation, because you almost always need it for grow in. I have tried to get a course built to 1970's standards, where there are automatic irrigation heads, but the pipe capacity is such that you can only program the fairways to run every second or third night, without much success.
Modern irrigation designers fear lawsuits, or bad recommendations from supers for designing a system that doesn't allow them to water as much as they may need in the worst conditions. Few will accept temporary browning as a condition of play. And in any case where commercial reality intrudes, having the large capacity just to speed grow in can be a necessity, as you use twice as much water for three months than you will ever use again. Not getting maturation can cost a year in opening, making the addtional $ for a bigger system pale in cost comparison to the lost revenues.