The owners manual maintenance schedule calls for spark plug inspection
(as I recall at 100,000 kms / 60,000 miles)
The customers who follow their schedule almost NEVER have a spark plug breaking/stuck problem.
Most folks don't want to bother to have plugs removed for inspection because "its running great"
What good could looking at the plugs do they think?
Why do you think Ford suggests to "inspect" plugs?
Probably cause it will allow easy removal later when they need replaced.. :W
Kind of like the old "Fram" ads..
you can pay me now (much less) OR you can pay me later..
have seen this go almost 8 hrs if several break off.