Tom,
Everybodies ground is different, so take this with a grain of salt. 57s on my place, won't work for a base. I gotta go big on the bottom, and little on the top. I had some entrances widened, and some roads on hills redone last year. My dozer guy, talked me in to doing it his way, and I haven't been sorry. He packed 23s with his dozer, and we drove on them for a few months. Then we spread 57s, and packed them. I swore by 3s on bottom, and dense grade until then. The 23s seem to work themselves in to a mat of rock. The 57s fall in what pore space there is, and you've got a good smooth surface with a base under it. I'd never heard of a 23 till he brought some. Do what you gotta do, but that way is working for me. Also, we had a mud washing rain about a month ago. I had to have him come redo stuff that had been in place for years. The 57s on 23s didn't even need a grader blade.