the whole show is based on this concept: they can send their agents back in time, but only seven days. when they have a problem with something, they can think of a way of how to solve it before it even arises, but it absolutely has to fit into the strict seven day frame. they're going on and on with that, one season after the other. and never one of them realises that there's no time restriction at all, because a week ago, seven days in the past, the agent could just walk into their hq, tell them the whole story and they would send him or another one further back through time.