Growing up I always assumed that the word tenure came from an old English word meaning 10 years. I’ve since looked it up and found the two have nothing in common. Nonetheless, tenure for a missionary seems to come at or around the ten year mark.
Tenure for a missionary is like tenure for a professor in the sense that getting tenure means you’re arriving at a kind of ensured longevity. But tenure is different from teaching because in teaching you get tenure for great teaching, research, or published scholarly articles. And as a missionary you get tenure for being broken down and wiped out, eventually staying in the field as just a shadow of what you once were. When the missionary gets tenure it means he finally lays himself down and really learns a slow dependance on the Lord.
You can tell the missionaries with tenure because the young and new missionaries all think of them as lazy, sometimes wondering why they are still around. Conversely the tenured missionary has patience for the young kid with an insatiable “go-get-em” attitude because he’s been there.
No one gets to tenure just by learning from the older generation. They have to get there the hard way—through long years of work and consistent failures from trying to operat without the Spirit.
Tenure is a good thing, the Lord can use the tenured differently because they’ve given up on doing things by their own strength.