Depends on the game. Ones where there's a vertical upkicker pounding into a hole (think monster bash) - absolutely.
It also depends on how anal you are about playfield condition - if some [potential] wear is acceptable to you on switch lanes for instance that are below ramp exits, no need to install those.
In any case, monitor the game (through regular cleaning and inspection) so that if you d notice wear you can make a decision then.