Accelerated teaching for late starters I agree with
@Lucy Chandhial that the pathway isn't different, just the amount of time needed. People from time to time in this group and elsewhere suggest that adults can learn as quickly as youngsters but I see no evidence of that at all, except for ringers who have been learning methods, compositions, etc all their lives and are still as good at is now as they were when they were younger.
Example from my own tower - adult, middle aged, been learning Cambridge Minor for more than two years, gets a plain course every week and has only just managed to keep a clean sheet. This person is not stupid, they succeed in life generally, but learning a method and remembering it from week to week just does not come easily. Compare that with the 15 year old who I asked to look at Cambridge Minor at the start of the practice a couple of weeks ago, and rang it that evening. Not faultless, but he put the mistakes down as part of the learning process and erased them such that now he can ring it without a mistake. I am sure the aforementioned adult would have learned it as quickly had he been learning methods when he was 15.
Practicing on a simulator does seem to be part of the answer. I know there's lots the sim doesn't teach you but if it helps to embed that line without the learning process needing other human beings then that's great. Adults generally tend not to like making mistakes in the company of others, while youngsters just see it as part of learning. When my daughter Charlie crashed her way through something a little while back after a sub-optimal amount of homework she just called it 'experiential learning'!