2003 and older would pop the plugs out. A easy fix and a new coil, and on your way.
2004, Ford went to a new split plug. It had a deep reach into the head and as a result would carbon up bad around the bottom half of the plug. Only time you had to worry is when it's being removed for tune. A lot will break and leave 1/2 the plug inside the head.
A good tech can make the repair but will cost $$. He does not have to pull the heads! Make sure to put 1 piece plugs back in and apply never-sieze to the bottom half for next time.
Ford did say to pull the plugs out at about 25,000 and apply the never-seize but most techs will install new one piece plus instead with never-seize.