I've been using the duck brand shelf liner since just after I started and learned it from several posts here.
There are basically 2 kinds - easy peel and and not so easy peel LOL
The 12" from what I can tell is the only easy peel available
The 18" liner is a good alternative, although it is not necessarily an easy peel product though it does come off fairly easily. However, it seem the glue on the 18" rolls is a bit tackier.
I bought 4 rolls of the 18" on sale at Amaz, and just bought 1 roll on Amaz of the 12"
I'm going to buy the 12" in bulk I think, because of the less "tackiness" of the glue.
The nice thing about the 18" roll is how many boards I can prep.
Unlike @Iguanadon I do mine a bit differently. Rather than roll out the whole board ( I can't get 12" boards here, but now I can get 14" boards from my new source), I roll the liner on the width of the board in several sheets.
I'm buying my boards now in 16' boards cut in half then in quarters, so I cut 2 18" x 14" pieces then a 14" x 12", and line them up and stick em'