I generally lay out temporary splits on the first ride- miles and 5Ks, unless the Red wants Kms- and check them on the second ride. I'll make permanent marks on a third trip over the coures, by car if the course allows it.
I agree with those who say that setting the splits is part of the job. One of the reasons I developed an interest in course measurement was the frustration of running on poorly marked courses. While the USATF certification process was developed to support record keeping, records aren't set at many races, and the main selling point to race directors is that a certified course is the right distance and that its splits are the right distance from each other.
An anecdote on the above: Earlier this year I measured a 5K/10K combo in the Chicago suburb of Aurora, Illinois- probably best known as the home of Wayne and Garth of "Wayne's World" fame. Aurora is along the Fox River, and the week before the race was wet enough to cause the Fox to rise and put portions of both courses under water.
The RD could not make contact with me the day before the race, so she had "high water" courses measured with a wheel. None of the intermediate splits were adjusted. The Chicago Area Runners Association gave her crap about it, so she had me come out late in the summer to do a "forensic measurement" on the courses they actually ran, and certify a high water alternative so the experience would't be repeated.
As it turns out, both of the courses used on race day were within a few meters of the advertised distances- but because the intermediate splits were off, the assumption was that the courses themselves were way off.
I'll certify a course without splits, because it's the start to finish distance that counts, but I sure won't measure one that way.