Do you have any post trim pics? I'd love to see them.
IMO, if the hoof is usually as long as the pictured one before the trim then he needs to be trimmed more often. Keeping the wall short is how you prevent cracks and chips. The hoofwall broke off due to it being too long and the leverage forces it to self trim.. Or you end up with flaring, which is worse than self trimming, btw..