Blade size is dictated by number, with smaller blades receiving the lesser rating. Tandem baits can come equipped with any combination of blades, two of the more popular ones being a small Colorado ahead of a larger Colorado or a small Colorado in front of a larger willowleaf. The size of the blades tend to coincide with the weight of the head. There may be instances in off-color water when a large, single blade might be more productive than two smaller blades, just like there might be times when hammered or fluted blades will be more productive than slick ones. Another element is wind.
Heavier baits are easier to cast and control in high wind than small ones.
The season of the year and the size of forage on which the bass are feeding can go a long way towards pinpointing the proper size lure. While bait size is certainly a key determinant in catching fish on spinnerbait consistently, color also is important. But don't be alarmed, here. There is no need to run out and purchase a spinnerbait in every hue under the sun. If you use a trailer, use one opposite the color of the skirt.