as a DM I always ask myself this question. Will the omition or addition of rules to my world cause unbalancing or will it make my PC's have to do alot of math. My friends for being in college have a hard time adding. Don't even get me started on huge battles. At most i will have each PC lead a sqaud (8-10 men) into a battle. Maybe even let one PC lead the army. Most times the PC's in my world prefer the hey we are the specialist sqaud in the army lets fly into the battle look for a enemy sqaud that is destroying normal troop formations and take em out, or even send them to take down the general of the opposing army and end the battle.