I never used the right side until he started adding the bend in the corner because they would always vibrate into the shooter lane causing airballs off the plunger. Now that he has, I use both pieces of the 2 piece set. I like protectors but do draw the line at full playfield mylar sheets.
I'd rather buy a new PF and hold onto it then cover the PF in mylar if the game is a life long keeper.