I have to disagree on a couple of points, first it didn't take three days to get a test shot, it took the worlds longest minute (later 90 seconds). The time it took to process a polaroid. Many of us can make an educated guess for a starting exposure with lighting gear we have used for any period of time. The OP shoots tethered to a computer as I do as much as possible. Generally I can get the lighting set with one additional shot beyond the first. Clients love having the computer to view the images as they come in, some use me just because they're offered that advantage. The computer also offers the opportunity to use the densitometer to set exposure across the image. When shooting interiors using HDR or modified HDR as I call it because I also use flash as part of the exposure it's especially helpful, a blown window will influence the histogram but can be ignored when measuring with the densitometer because it will be replaced with a properly exposed image and combined later. I just need to get the part of the image I'm going to keep properly exposed and ignore the rest.
I used to never judge density or color on a polaroid just comp and shadows. And we would send test 4X5s to the lab to see how their run was going that day. It would take usually less than an hour to get transparencies back and we would adjust filtration and exposure per the test run.
I ALWAYS use a flash meter. It saves time and takes all the guess work out of the process. Its great for NAILING ratios and most of the time I don't have time to be screwing with adjusting ratios in the shoot.



