How do you successfully lead an assault on a town/castle?

It almost seems like a game of whether or not the siege engines last long enough until the battering ram reaches the door. Everytime I try to siege a settlement; I always ensure that I have all siege engines are reserved and ready to deploy with the caveat of the ai building more defensive weapons, however I find that it’s almost a guaranteed loss if only a couple siege engines are built on my side since they’ll effectively get destroyed by one or two defensive weapons by the enemy thus I always build all siege engines to their capacity each time.

The problem is the fact that these built up siege weapons ballista/onager/catapult don’t actually deal any damage to enemy defensive weapons thus they eventually get destroyed by the enemy. The funny thing is, siege towers are always destroyed first so it’s almost a meat tank in a way. Besides that, once the battering ram and the two siege towers are destroyed I’m always left there with a disproportionate amount of troops left compared to the enemy after being bombarded with defensive enemies resulting in a loss. Is it just me or does the ai just suck at targeting enemy defences?

I’m playing on bannerlord difficulty btw so that’s probably one of the reasons, also I don’t have any focus on engineering tree nor do i have a companion for this task since I have all of them caravaneering for gold sustain.