I completely understand what you are talking about and your solution makes sense to me. However, perhaps it would be more appropriate to use that style for different units depending on general discipline. It would make sense that Roman cohorts and other highly trained units would place great emphasis on maintaining formation at all times, especially before closing to combat. At the same time, poorly trained units and non-cohesive barbarian units would be more likely to just charge in piecemeal. This would give added flavor to the units as well.