Backer Boards

How do you backer guys fir the walls out when using shower pan with mortar. I have only done it once and used left over pan stapled to studs. What are some other trade tricks.

Not sure I understand the question but typically the studs can be firred-out 1/4" (with lattice) to within about 6-9 inches of the bottom so that the pan liner has room to tuck [under the lattice] and attach directly to the wall studs near the top of the liner material.

I use only Kerdi now, no need to screw around with liners.

But yes, lattice or 1/4" thick X 4' strips of wood sold in bundles for a few bucks at HD.