i dont think that i really agree with much of what you are saying about size. i know thats a pretty common thought among the fishing community but from my experience size plays a much smaller role than other variables.  i stick with pretty much the same size all year round. in the spring my lures are a little larger than the spawn so they stick out, an easier meal. in the fall they are smaller than the young of the year, so they stick out, smaller generally means weaker. in the spring i retrieve more slowly. cold water means fish dont move as well, so an easier big meal is better than a smaller faster one. fall i use a more erratic retrieve.

with that said, again i prefer shad shaped lures over minnow lures of the same length. i like the larger profile, more flash, more vibration. if that means larger?