Protectors seem to help in the shooter lanes, near eject holes, and in places like the scoops on games like Funhouse and TOTAN. Like others have said, it depends on how many games you play on each machine at home, and the condition of the playfield when you acquire the game, and how willing you are to have it degrade some over time. Hard to imagine, but just 200 games and you'll see visible wear in problem areas. Most enthusiasts will spend the small bucks to get protectors for those key areas. If you just want to run your machines till the wheels fall off, then there is no major reason to get protectors. (In a few cases, like near the Bazaar Scoop on a TOTAN you may find the degrading playfield begins to catch the ball as it gets wedged between the wood and the steel, but your mileage may vary).