Games like Age of Empires tend to encourage a tactical rock-paper-scissors (crossbow beats sword beats pike beats horse beats crossbow) kind of approach down to quite a detailed level, with units having very specific strengths and weaknesses against each other. To what extent was this reflected on the actual medieval battlefield? Do you equip people based on your likely opponent ("We're at war with England! Quick, what's the hard counter to longbows")? In the middle of battle, to what extent could this be managed effectively ("Look, there's some pikemen - where have the archers gotten to")?