With proper maintenance intervals and the use of high quality oil/filters the timing drive system should never require replacement for the life of the vehicle. This is due to the fact that with proper lubrication, the friction in the system is minimal.
As far as the SSM to replace the phasers, it specifically states that other camshaft timing related components should not be replaced unless inspection identifies a concern. Which means that if a tensioner sticks upon retraction or a guide is cracked (for example) the technician has approval from Ford to replace the affected component. I would not be concerned about tensioners, chains, or guides with low mileage on these vehicles. A faulty phaser locking pin will do nothing aside from make noise; it doesn't affect cam drive operation or durability.