Note that it is only when the images are combined that the color information is mapped as red, green, and blue pixels. This image also represents one of the best of its type in the world. Click HERE to see the final color production of this image. On average, perhaps 2 to 4 high quality LRGB images can be completed on a given night. Keep in mind that most amateur astronomers that take pictures in this way would spend an entire session on a single target, and then process the image later.
Color images are quite an investment in time.
Then, all these images must be combined. Dark frames are taken at the telescope on your night. It has been found that a library of master darks would be impossible to create and maintain. On a normal night the time devoted to dark frames is less than 30 minutes. As a last resort, morning twilight can be used to create darks, but this is risky since all image combining would be delayed until that time.