I often stand off from editing photos from a session for a little while, but not always. A lot of this I think has to do with the the strength of the images to begin with. How many times have you taken a picture that you think is the cats pajamas only to look at it a bit and realize that it doesnt cut muster? Similarly i often review older images and find ones that i felt pretty ho-hum about but in retrospect find a gem. So, my pause is simply to be able to approach the subject matter a bit more subjectively than i would if I jumped into them right after shooting. Often once I've been out on a shoot, I am full of ideas, some of which I will write down and I have found that working too close to when I took the pictures doesn't always let me really think about the best ways to achieve what I want. And then there are those times I like an image, but just don't know if I have the technical ability to deal with it so spend time researching technical approaches.