Smokecat- I don't purposely dry anything out, but I keep my bins a lot dryer than others I've seen. Rather than keeping a lid on, I just pile the bedding on thick. The bedding on top gets very dry, but it acts as a mulch and conserves the moisture deeper in the bin. I rarely add any moisture at all, other than what is in the food scraps I feed. I also stop feeding the bins for at least two weeks before harvesting, and do not add any moisture during this time. The mulch/bedding layer holds in plenty of moisture to keep the worms happy during this time.
What I'm left with is moist/damp (NOT mucky/muddy), "granular" worm castings that aren't all stuck together. They sift really easily like this. Each bin takes me about 15-20 minutes to harvest.