One of my photography books shows three different prints made from different negatives, but of the same subject. In producing the prints the only variable was the agitation of the film during processing: the first received "normal agitation", the second received no agitation and the third received constant agitation. The normally agitated negative is advocated as the best. But I wonder. The problem with "normal agitation" is the difficulty in achieving consistency. The book suggests "...inverting and righting the tank with a twisting motion of your wrist. Turn the tank completely upside down, then reverse the process..." Something of a mouthful and not completely clear at first reading. The purpose of agitation is to keep fresh developer in contact with the film. Continuous agitation would seem to be a better approach. Placing the tank on a motorized set of rollers, similar to a rock tumbler, comes to mind. Of the three prints, the no-agitation one seems dark, the continuously agitated one seems light, implying that the negatives were too light and too dark respectively. In other words, it appears that the continuously agitated negative is over developed. I.e., the processing time needs to be shortened. How much shorter probably can only be determined by experimentation.