Mindset (for lack of a better term) can offset training and experience.
Lets take paratroopers (which have been mentioned a couple times in this discussion).
During WWII American Paratroopers were involved in some of the most fierce combat in the war, yet, they had a much less rate of PTSD.
The army asked that question. Except for airborne school, airborne infantry go through the same training and any other American infantry troops so what is the difference.
The army went to Benning to study this and concentrated on the 34 ft tower. Any one who's been to jump school can attest that the 34ft tower is more frightening then actual jumping from a plane.
They found those who were slow to jump from the tower were twice as likely to fail or drop out then those who were quick to jump. So what you end up with when you talk about paratroopers is a higher percentages of "fast jumpers".
An example, someone mentioned we, America, fights different, and technology, air power, etc, makes the difference when comparing American Soldiers and others. This is true to a point, but then again the paratrooper example proves that's not always the case.
Look at Bastonge. You had one understrength light infantry division (paratrooper) holding off three heavy armor divisions. Weather prevented air support and re-supply, but paratrooper mentality allowed them to prevail.
Another factor that comes in to play that skips "training and experience" is control. If you feel you are in control of your fate, you are in a much better position to work through the problem, where if you aren't in control, fear interferes.
Take bomber crews in WWII. Percentage wise they had a pretty high causality rate. When under attack pilots faired better then turret gunners. They had the feeling they had control of their destiny where the turret gunner could do nothing but set there, leaving his fate to someone else.
If I may interject a "war story" it would help explain the "control of ones fate" theory.
In March 1968 I was involved in one of the worse firefights of my tour in SE Asia. I did fine, meaning I could set aside fear because at the time I was carrying a M-60, and I had control of what was happening around me. That is until I burned up the gun. Now I'm helpless, I had nothing but a 1911a1 and could Basicly just set there. That's when the worse fear of my life kicked in causing me to sort of freeze up. The only way I could control my fear was when a M16 from a fallen comrade became available and I could get back in the fight, I then felt I was back in control of my fate and again could work through my fears.
Experience may or may not help. I had experience of setting there with the 1911 which would help nothing. I had experience with the '60 and later the M16, which did help.
Where training comes in, is with training you are given the tools where you can gain control of your fate.
Experience is good if you can "after action" your conduct, meaning you have to evaluate your actions. Your failing in your experience means you have to train to prevent the failings in the future. You success in your experience needs to be studied to determine what you did right, and if possible expand on it.
In my "war story" mentioned above, if evaluated correctly I would had determined the time between the M60 and M16 should have been spent in a more aggressive roll. I did the evaluation and I think it helped me a lot in the rest of my tour.
In continuing my military and LE career in my future life I took the lessens learned (good and bad) and incorporated it in my personal training and the training I provided to others.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071