Oh size and shape absolutely can dictate tactics! For example, larger shields can offer more comprehensive protection, allowing a team to form a shield wall- but its hard to move. Check out all the different types of medieval shields for an idea of how others designed around this concept. Remember, this can change your overall gameplay.

When we consider the effect of shields on team tactics it is cool to draw parallels with military history. Throughout history, one sees cultures create long shield walls when the people are working together in sync which increases the efficiency of the group overall.