Wow, I read all the posts.
I tried actions once for watermarking, and just couldnt do it. I get as close to what I want in camera first and worry about everything else in PS. I agree with the OP when he says that each image is like a writing. There are subtle differences from one photo to another. I believe I have a form of CDO (that's, OCD in the order it should be) that makes me want to look at each individual shot and adjust it.
Mainly the white balance in landscapes. If I'm shooting something with the same lighting the whole time, I would get the kevlin degrees right and batch watermarks or whatever needed to be done. As for most everything else I shoot, I adjust white balance later, picture by picture, minute by minute. Sometimes, for a certian picture, i want 4500 and another I want 6000, even though they are in the same lighting. I found myself doing that more and more for fall pictures. I may want to enhance the reds or something in one shot, so I increase the kelvin degrees to get that effect.
~Michael~