merlyn: "Can you dehydrate foods too much? I worry about not drying long enough and having meals spoil. I have a small (5 or 6 tray) dryer and since I'm drying complete meals I made I don't have a timing guide. Can I just leave it on over night?"
I have heard a few people say that overdrying removes flavor, but I don't think that's anything other than an opinion. I often leave my dehydrator going overnight and haven't noticed an issue. It isn't like dehydrated food is super flavorful anyway, and out in the woods it all tastes pretty good.
For some foods, like apples and such, if you want food to be a bit chewy, then you don't want to over dry them.