In a particularly dusty area 12k miles could be the needed AF interval. Otoh as the previously posted link 67k mile AF anecdote indicates, one can have a filter that visually may appear to be loaded however not be restrictive as measured by a filterminder. As comparison only, in my observation the 67k filter linked visually appears more loaded than the topic filter.
I don't live a particularly dusty area. OM AF interval recommendation ~30k miles and as noted in the link, used to be the norm for me. After the linked post buoyed by Jim Allen's comments and knowing AF's become more efficient with use, I'm not afraid to take it a tad beyond that. Though purely subjective, similar/same engine performance before and after the AF change.