I love formation! Can't imagine Brytenwalda without formation,
Formation just need a bit of tweak to fix some error, that's all.
Playing native, each time at the start of battle you need to press at least 2 button to hold your army, and 6-8 more button just to separate your battle group.
Letting your troop charging the enemy at the start of battle is fine as long as you are playing easy diff/ faction with knight.
Try to raise your difficulty setting if you can win every battle by letting your troop charging blindly at the enemy.