For example, there have been a few cases where I've requested a mission, then canceled out of the bestowal dialog because I realized I wanted to do some logistics first, then come back in and it will no longer give me missions.
Ohter times I've just run out of missions really fast in a system, and in others It'll let me keep going for a great many before it runs out - but I've found no rhyme or reason to this.
In any case, I usually end up being cut off of available escort missions long before I've grown tired of them. I really like the new pirate destroyers you occasionally run into during these missions.
