I would say my number one blade shape is Colorado, followed by Chopper (Pear shaped), Indiana, Hatchet (in summer) and last would be Willowleaf. I have had good luck on Willows at Green Bay – but in general they are not a top producer for walleyes. As far as when to use what – experiment. Use a quick change style clevis so you pop off and on blades quickly to change things up.
Downsizing blades can help – but I think speed changes can be more effective. Just remember, speed changes will also change the depth you spinners are running – slower will be deeper, faster will be shallower so you might have to adjust line out to stay in the right zone. I think if there is one common thing I see – cold fronts usually move the fish closer to the bottom.