Motivation, sure. Full time focus during those three months. A lot of people will say that they've studied a language for a certain number of months or years bu

Motivation, sure. Full time focus during those three months. A lot of people will say that they've studied a language for a certain number of months or years but how many hours have they put in over that time? I think the biggest thing is that you're likely seeing them after a few weeks in country, remember that these guys have to get out and do their pitch for 8+ hours a day, every day. So their command of basic greetings, introductions, and specialised religious and other context appropriate vocabulary would be expected to get better very quickly.