They can provide a vast pool of resources for huge events, like evangelism at the Olympics. Meeting short-termers may encourage nationals in their own witness. It takes time to learn a language. It takes time to fall into the ground as a seed and lose our life, only to find it again in a hundredfold growth among another people. If love and listening require time anywhere, how much more this is the case when cultural contexts are radically different.
Foreign life is neither exotic nor simply a cauldron of problems.
Foreign life is merely another set of arrangements viewed best through local lenses. It takes time to adapt to this. And it takes time to absorb how to make local patterns work. These patterns are not mastered in the first week off the plane. God in Christ took 33 years in one place.