Because I was getting a new tire and plan a very long trip this summer, I decided to lube my driveshaft splines way ahead of schedule. My K75RT has 76,000 miles on it and has had Honda Moly 60 paste on all splines for 25,000 miles. The driveshaft was last lubed 5,000 miles ago and 11,000 miles before that. Upon inspection the rear shaft spline (female) and rear drive spline (male) still had lube on all surfaces, and there was no evidence of dryness. Much of the remaining lube was still greyish in color. When I checked it the last time (11,000 miles) the color was more blackish and there was less lube on the splines. The rear drive splines look as good as new. The rear spline of the shaft looked very good with no clear evidence of wear. Because of its darker color and female design it is harder to judge. The back splines were so well lubed I didn't bother with the front ones. Based on what I've seen, 10,000 miles would be a good interval for lubing all the driveshaft splines.
In addition to using a different lube than that recommended in the FAQ instructions by John Diaz et al, I used a slightly different procedure to get to the splines. Brian Curry shared it with me at Daytona, and he got it from Anton Largiarder. This method is much easier than the standard way and should be included in the FAQ writeup IMO. I'd also suggest that BMW #10 may not be the way to go on older, out of warranty bikes. Many prezzes use a moly fortified lube.