We also have to remember that it is easy to adjust if you have the right therapy, medication, and you are not around constant reminders. Ideally they should send everyone to a deserted tropical island for a month on return. Some good eating, relaxing and a month worth of therapy would be good for the sole.
I heard someone talking about 'Adjustment Disorder' on this forum. They actually have a name for it now but not when I was serving, so I think everyone goes through it.
Look at it in other perspectives. Prisoners who have been locked away for over three months, astronauts who have been on the space station, and even those navy types who chose to live in submarines whould all suffer from a type of adjustment disorder, its natural, you body has retrained. Even people who do shift work for six months or more have trouble adjusting, so its nothing new.
PTSD is a totally different kettle of fish, that is why I think veterans with PTSD suffer from the Adjustment Disorder for a bit longer.
Just an opinion.