I understand putting an overdrive in front of a distortion pedal but I've seen people with boards having 4 or 5 different distortion pedals lined up. Is it normal to stack more than 2 distortion pedals together? At what point to you hit diminishing returns with your signal being altered? How do you know what affect each pedal is having if you've got more than a few stacked? Are there rules of thumb people follow (like OD before distortion)?