I've been trying to get faster and more loose in Zbrush, so I started making "quick" sketches using the Dynamesh feature. Each sketch started from the base spheres shown in the center. Some only took 15 minutes to make. Some took up to 30 minutes. I know there are some great zBrush artists out there that can work much faster than that, but for me, this is a great improvement over my old speeds.