Keeping exposure timing less than a half second has another benefit other than tack sharp leaves and branches. If someone inadvertently walks into your long exposure waterfall framing, you take that opportunity and include that person into your photo with less probability of that person will blur out.
I was so happy to take this shot. The person in the photo counterbalances the waterfall in the overall structure of the composition. This balance shifts the attention away from the waterfall as the main subject adds another dimension to the composition, which will be otherwise a predictable and bland photo.