Steve,
I don't know if you will catch this follow-up or not.
I gave some more thought to your question while I was wandering around the Monocacy this morning. Given a choice, I would really prefer to set up and wait for the birds. That requires a couple things not the least of which is the unbridled confidence that if I wait, the birds will come. I had that confidence a month or so ago. But when the birds didn't come for a couple of consecutive evenings out, that confidence was shaken and I started moving about more.
All in all, I think it is much more difficult to catch the shots when moving about - particularly when using a tripod, etc. As I said, and I saw it again today, I could stop with the tripod on my shoulder and look at the bird and usually it stays. As soon as I lower the tripod from my shoulder, the bird often takes flight. It just happens. I missed a couple of warblers and thrushes that way today. On the other hand, if you are shooting handheld, it may not be as big of a problem. I say that knowing that before becoming wedded to the tripod, I found the act of lifting the camera and big white lens was sometimes enough to send the bird scurrying away.
Then there is the wild card in all this. Often my wife, who is more the birder in the family, accompanies me on my forays and she gets antsy when I hang in one place to long. Consequently I am much more likely to move around when she is with me which is probably 3 out of 4 times.
Hope this helps or at least doesn't add to the confusion! 
