It is not really bluffing if a surgeon says you should wait 4-8 months, because swelling can also deminish your sensation. I had for example a stagnation in my recovery in the 3rd month, but in the 4th month I got really a boost in my recovery. I would say holding your judgment until the 12th month is a good attitude. After that I would consider as too long for a human being to wait more.
That's an interesting test; if they tested a few thousand jaw surgery patients like that, I'd be curious to see the results. Re: recovery, obviously there are individual differences, I'm sure some people experience improvement even after several months but that does not seem to be the rule.
Anyway, I did some research and found this study that is interesting to me:
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0091055. "The incidences of subjective NSD [neurosensory disturbance] after maxillary procedures were 16.2%, 13% and 9.8% at post-operative 6 months, 12 months and 24 months, respectively; the incidences of subjective NSD after mandibular procedures were 35.4%, 36.6% and 34.6% at post-operative 6 months, 12 months and 24 months, respectively." So according to this, patients have a realistic chance to recover from nerve damage caused by upper jaw surgery, whereas those who reported damage from lower jaw surgery at 6 months post op, seemed to have the same problem 2 years post op (and the rate was roughly one in three patients; 35%). Another interesting sentence from the study: "Although a systematic review showed 12.8% of the patients had persistent NSD [neurosensory disturbance] by objective measurement after an orthognathic surgical procedure, the reported incidences of subjective NSD after orthognathic surgery varied in the literature and could be as high as 87%".