Oh, that theory has a lot of merit, Bemused.
In most cases, candidates were not forced to go to any particular field. We chose our future field of service as we progressed through the training.
Missionaries on furlough were encouraged to visit training centers, and we students could attend meetings, hear presentations, meet the missionaries in person, and even have them in our homes for meals.
So yes, trainees had opportunity to get a feel for the "personality" of particular fields. I know that I formed definite impressions, based on people I met (including MKs from that field), things that were said, written in mission publications, and prayer requests in Hold the Ropes. There were fields I said I would never go to, and this was all based on impressions I had of what the missionaries on the field were like.
One of the fields I said I would never go to?
Papua New Guinea.