Question: At the beginning of the move it is established that Big Jake has not seen his sons for 10 years, but it appears he is close enough geographically to be found, summoned and arrive before the bad guys can get more than a days' ride away from the ranch. Was he really that bad of a dad or is his arrival at the ranch a bit too magical?
Answer: It doesn't help explain locating Big Jake or time involved, but as to helping some with the quickness of him coming to help, remember he came in on a train, he didn't ride back home.
Answer: He has been gone for 10 years but knows "Juan and the little boy", not 10 years old I assume.