not fleet pride.
shaft design is a function of design constraints and angles, double cardan is for when all the angle is at the tcase, and you're running within about 3˚ of 0 angle (minimum 1˚) from pinion to shaft.
single joints are for when pinion angle to shaft and case angle to shaft match, in either direction (4˚ down from case to shaft and 4˚ up from shaft to pinion, or down and then down)