While in Charleston, South Carolina I was in an impressionistic mood one afternoon. For these images I played with different amounts of camera movement to mush the detail to varying degrees. With the azalea image I wanted the detail just slightly blurred so that the individual flowers didn't become too abstract. The shutter speed was 0.5 seconds. What I particularly like about the motion blur is how it smeared the Spanish moss which created a bit of haze that added to the mood of the image. For any camera motion technique I shoot a lot of images with the expectation to end up with a couple keepers. Each one is different and I like to have a lot to choose from since this technique is half art and half science.
The exposure for the bamboo abstract was 2 seconds. I chose a slower shutter speed because I wanted a more heavily blurred image. For both photos I moved the camera up and down very slightly - a little movement goes a long way. There was also a practical reason that I blurred the bamboo. People's initials, names, etc were carved into the bamboo and with a sharp image this would have been painfully obvious. Conveniently the motion blur did away with those unsightly distractions. As you can see the shutter speeds used for these techniques can vary significantly. Depending on the preferred look and particular technique being used I'd say anything from 1/15 of a second, down to a couple seconds is fair game.