I logged my first two benchmarks this past weekend. The online descriptions do not always meet reality. In my case, I was able to log two that were about fifty feet apart. Reading the online descriptions was quite interesting, but the actual benchmarks were three foot masts, one inch in diameter. Not even close to the online description.
I found another partial 'benchmark' on my way to the cache - that was not listed. Keep looking, they are out there somewhere and always neat to find.