Along with everyone else, I await, anxiously, improvement in sieges.
I start off by wondering: why do I build my siege engines within range of the enemy engines?? If I can move them, ahem, TO RESERVE - why not build them there and move them up only when they are all built, or an assault is made?? (Yeh, I know they aren't showing them on wheels, but they're getting moved in the game already, so what the heck?)
Anyone EVER set a fire of longer duration than 1 second with a flame ballista or catapult? Yeah, me neither. And why aren't the defenders trying to burn my approaching towers and rams? Because they can't set fires either.
I'm dismayed but not surprised when enemy rocks take out a tower or ram. (Fortunes of war, and all that.) I'm dismayed AND surprised when my own siege engines break them, especially when loaded with troops. Why can't they be targeted counterbattery, instead of at the stretch of wall I am assaulting?? Happens too often.
I always bring at least 2 quivers and usually 3 for my character. I usually use all my arrows up, then scour the battlefield for individual shafts to send back. WHY THE HECK DON'T ATTACKERS BOTHER TO BRING ARROW BARRELS??? I normally wait until my guys clear the local war to make it reasonably safe to mount the ladder/tower and ransack enemy arrow barrels on their ramparts. That may include "stirring the pot" as another has mentioned. Just shouldering back and forth thru the crowd at the base often gets the flow moving again up the ladders.
Personally, I often see 2 ladders in a tower in use at once, and occasionally 3. I agree it would be a sad thing if only one is being used.
As a high-skill archer, I rather like it when the enemy assaults the tower head and appears at the top of the ladders. They're easier to snipe there than trying to hit among the Brownian motion on the ramparts, from below. But I'm grateful for enemy archers, who seldom take cover when I plunk my first arrow into their bodies, and I need not reset my aim to hit again and finish them off. Oh, and I'm very good at face strikes, which usually one-shots them.
Despite all the difficulties, it's exceedingly rare for me to lose as many dead as the defenders, and I often have fewer wounded, too. I've read how to cheese the AI with retreats, etc., but I don't care to give up entirely on the game as simulation.