Tim,
I recently learned that it can be a legal issue to use older temp and precipitation guides for design. Since most believe climate change has changed weather patterns, using a precipitation guide that Toro put out not long after WWII could be seen as Malpractice in irrigation design, and using older rainfall charts to design drainage would be similar. I think a lawyer could have a field day if a gca pulled out an old, worn, paper copy of some design data.
Many agreements now have "resilient design" clauses and if your course floods or is brown part of the year, someone may think you are not doing your job. I would hate to have back to back 100 year storms when I designed the drainage for a 1, 2, or maybe 5 year storm at most without contractual protection of some kind. (BTW, I am currently combing multiple sources to provide such a clause for ASGCA members to use in any updated contract)
And I always joked that a golfer might sue an architect or super for losing a bet someday. It might be a good defense to say you used the best tech available in setting that cup that cost him thousands of dollars. I know of one CA club that sued its renovation architect over one green that they deemed didn't have enough cup setting areas. (I don't know the outcome)