Sarne1e,
It was, and is up to a couple of years ago, rare for USMC to send pilots and aircrew to WTI before sending them to a type school Top Gun/USAF FWS for Hornets or AATTS for Herks. I really never figured out where/what Lawn darts and Queers did as pre-WTI.
The basic theory is to first start out as say an instrument instructor, then NATOPS, FCF, etc. in order to see is someone made a good instructor and not waste resources. No one long school to cover all instructor sub specialties but a block approach.
In my experience the USAF courses were all brief/de-brief. Regurgitate exactly what was passed in class and no understanding of why or deviation allowed. The actual flight portion seemingly to be irrelevant. The normal USAF barb thrown at Marines was along the lines of “you’re counting electrons and need to know how everything actually works”.
I think you’re being charitable on the quality of those Marines on exchange tours. Most not being competitive for promotion or more than basic qualifications. More than a few only received qualifications after being the only volunteer for an exchange slot. Individuals orders coming down from DoD via HQMC directing such individuals to be qualified in XYZ.
S/F, FOG