Game of Thrones Season 8 - Fire your Accountant: The numbers don't add up!

Jon Snow and the forces of the North along with many other kingdoms went to help fight off the Undead.  In a desperate struggle, we see a great army assembled with irregular Cavalry in the middle - exactly where they shouldn't be.  They are facing off against a larger army of the undead by what seems to be a factor of 10+.  The battle starts as a horde of Dothraki Cavalry charge steady infantry (essentially) Frontally.  

Historically, the idea behind this might be to shake the enemy morale enough to disrupt their lines and exploit a weakness that can be punched through on a follow up attack.  

There are 2 reasons why this doesn't make sense.   
1) The undead don't suffer "Morale" issues. and
2) There isn't going to be a follow up attack because the troops aren't attacking.

The best use of light cavalry would have been to attack the flanks or send the horses away and use those soldiers as ground troops.

The fight was epic and full of action.  The castle was overrun.  A few hold out heroes were fighting against overwhelming odds.  Heroes were sneaking along the crypts just to survive.  Many died in this battle and, what seemed to be only a handful of survivors lived.  

The original idea was that Cersi would take advantage of a decimated army having beaten itself up supremely against the Night King.  This would have been perfectly evil and within her character...and the numbers would have made sense.  

Maybe with Jon, he would have picked up more support as he travelled south but the 'Unsullied' were finite and Dany certainly wouldn't have "Held several thousand back" if she was fighting for her life.   

 At the funeral pyres there were A LOT more alive than was even possible and, THEN, Somehow, they managed to dig up enough soldiers to march down and take on King's Landing!

On the way sailing down, one dragon and all the Dothraki were seemingly destroyed on the water by the 'Iron Fleet' and their hot new weapon "The Scorpion".  At the battle of King's Landing, several more THOUSAND Dothraki SOMEHOW appear to fight in THAT!!!  

Maybe the Dothraki are related to Wile E Coyote and can die many times but keep showing up in the next scene.

HOW DID THEY FIGHT TO A MAN IN WINTERFELL AND PULL AN ARMY TOGETHER GREAT ENOUGH TO TAKE ON KING'S LANDING IN A FEW WEEKS!?  

During the battle for King's Landing, we discovered that the dragon's breath also has an explosive effect on stone buildings.  Seriously?  Don't get me wrong, it LOOKS pretty cool but logic is, obviously, the greatest causality of this series.  

The acting and directing are awesome but, I have to wonder.  This looks more like Fan-Fic for its lack of congruity.