Have your read through the 'Exclusions Section'?
Every policy has what is covered and the 'exclusion' part.
Some covered parts are not covered if a non-covered part fails causing damage to covered part.
Some covered parts are not covered under certain incidents.......act of God.
Some covered parts are only covered for certain amount of time.
Point is.....every policy is written by them, for them.......not you
Best you can do is read the fine print/exclusions and then decide IF the other part of policy is cost beneficial to you.