I agree with much of the above, but I'd put it in a somewhat different context. I am a long term fantasy and science fiction fan. In another thread I mentioned a rule promulgated by Ursula K. Le Guin, whom I regard as one of the best writers ever to work in these fields. The rule says that you get to create your own universe, but then you have to follow the rules of this universe. By the very reasonable standards of this rule, the show runners of GoT have failed badly. If dragons are born in season 1, and then dragons grow big and strong in the following seasons, then that is to be expected. If, however, the members of Dany's team are smart, even brilliant, in the early seasons, then they turn into dunces in Season 7, that is unacceptable.
There are multiple problems with the battle we are considering in this thread. One (and I do mean only one) is the fact that it occurs so late in the game. Jaime, Bron, Lord Randyll, and a considerable force of men move most of the way across a continent, and none of their enemies realize that this is happening. The bogus "surprise" nature of the attack on Highgarden is not believable. After the castle falls, the wagons loaded with gold trundle slowly all the way back (or essentially all the way back) to King's Landing before the dunces on Dragonstone rouse themselves to action.
Nah, this is baloney, and my objection is not a matter of nit picking. If the story telling in GoT had remained adequate, then the battle of the wagons would have occurred much earlier, and it would have been decisive.