The way I do mine is definately a one person assembly line. Bake them all one day and stack them in tins after they've cooled. Next day I start the first layer of flooding. During the month of december, i had 64 dozen cookies to do and the quickest way I found to do them Is to do as much as one color as you can before moving onto the next color. meaning, I had trees, dresses, themed shaped cookies, that all needed green flooding so i did all those then moved onto the next stack of cookies that needed a different color flooding. then after a few hours, could go back and do all the decorations on top of the flooding.
here's a link to the page of some of the ones I did in Dec.http://www.flickr.com/photos/alycakes/page2/
the rest of them are on the next page.
I could flood a dozen in just under an hour. most of my cookies are 4". The decoration part of them took about 20 to 30 min per dozen. some less time just depending on the details.
here's one of my techniques don't know if anyone else uses them. I found it a pain to have one color with two different consistancies, one for outlining the flooding area and one for flooding. saw that on here somewhere when i started cookies. I make a medium flooding consistancy, outline what i'm flooding and use a paint brush to "pull in" the icing to the middle. just keep it in a little cup of water. just make sure that you don't add too much water with your brush or you'll get white streaks on them. for round cookies, a spoon works great.
hope this helps.