In Inception, one of the last scenes (and actually the very beginning scene) is Saito being approached by Cobb to both retrieve him and remind him about their arrangement.
But did that action really matter, besides getting Saito out of limbo sooner than him just dying in Limbo (is that even possible, hence the problem with being so deep?)?
It seems that without Cobb directly rescuing Saito from limbo, he would have just died of old age, woken up in reality after mere minutes due to time dilation theory and shaken it off. It would still have worked out fine for Cobb. Saito experiences a few extra years of subconscious deep level dreaming, but in reality only a few minutes later... still wakes up and can "make the call" before the plane touches down.
Why was it necessary for Cobb to go looking for him and drag him out of limbo forcefully?