Troy,
I would love to know the background that spawns your answer.
While I can agree with your premise, I think lesser systems (not coverage but GPM) would encourage deeper, infrequent watering, because the super would HAVE to only water part of the course. What I have found is that those 2500 (and higher) GPM systems allow the super to use it every night for overwatering, rather than save it up for deep, infrequent watering. There are as many consequences to overwatering (disease, environmental criticisms, and even poa invasion at a quicker rate) as there are to underwatering, although I can't recall a case of direct turf death from overwatering.....
With a lesser system, why can't we, as Forrest suggests, go back to a 1960's watering schedule of watering deeply every other night to half the course each? Even every other night is not exactly "infrequent." I know committed supers who water every fourth night with no ill effects. And for most courses, (up to 99.5%) and golfers, a bit of difference from one fw to the next would not be noticeable.
I specifically disagree with designing for the "worst case scenario" of a 100 degree day in six hours. If (depending on climate, as I am thinking about the midwest, not the desert) you have a few days a year where it could take up to 10-12 hours to water the course, you would lose some play, but the initial cost would be far less. If you saved $250K in pump station and pipe costs, and were paying $20K annually in interest on that, and were getting an average of $50 per player then you would have to lose 4000 rounds, or twenty full days (or more likely 40 half days) of play to break even. In most areas, there just aren't that many days of weather causing above the normal need for irrigation.
That is how I justify using less than the top of the line systems you propose. Somehow, as Forrest notes, we made it through until the 1990's without watering courses in six hours every night, and I propose that we could do that again.
Again, please realize that my ideas are for affordable courses, not Trump type extravaganzas where the owner would never settle for less than the best. It is also where climate and soils allow. However, this is an affordable golf thread. One way to make courses more affordable is for supers, gca's, and irrigation designers to tell the owner that there are possible consequences (and work arounds) to not having an overkill irrigation system, (and in the supers case, to please not fire him for a drought) but that if he/she is willing to live with those, then we don't need to spend hundreds of thousands to cover the behind of either the irrigation designer or super.