Whoever created the battle strategy for Winterfell has never played Total War or Stronghold ...
- Whose first move is to send their cavalry into massed infantry in a head on charge before they've even started using ranged weapons and then engaged with infantry? - Who puts their catapults out in front of their infantry? - Who builds castle walls full of handholds and footholds for the enemy? - Who allows the enemy to scale their walls without covering them in boiling oil or at least parking a fire breathing dragon there to scorch them off? - Whose moat (in this case of fire) can by crossed by a couple of infantry laying across it? - Who protects a High Value Capture Point (Bran in Godswood) in close quarters combat with only a few archers?
And don't get me started on the whole 'who the hell lands their dragon on the ground during a battle' question.
Ultimately there's only one thing that really can be said about this issue:
Dramatic effect was a much higher priority than military tactics realism when it came to writing and planning out the battle for the episode.
“Whoever fights monsters should see to it that in the process he does not become a monster. And if you gaze long enough into an abyss, the abyss will gaze back into you.”