Ive always shipped fillers mounted to a flange we cut on the CNC. The filler, and toe kick filler are pocket screwed to that flange that gets screwed to the exterior of the cab.
The bulk of the commercial contractors I feed say fillers from others just land as the filler alone (2" x XX" filler strip) like you get with residential solid wood cabs and they drill and screw from the inside of the cabinet. I have no idea what they do in that situation to fill the gap in the kick for vinyl cove but ive seen these after install and while I know no one in the commercial world cares but the butchered holes inside the cabs always look less than optimal.
New contractor picked up a batch of cabs this morning and said they just always buy metal angle brackets and attach the fillers from the back!!!! When I handed them the fillers we normally supply with the flange, filler, and kick filler, they were over the moon. That said, the last couple jobs for our normal contractors I quit supplying the flanged option and just shipped whatever fillers were needed.
Typical situation that I dont want to cut/ship something I dont need to and most commercial installs I see even from massive shops that do their own install are far from anything I would walk away from (no offense but Ive seen pretty high dollar jobs where a screwdriver was not even contemplated to adjust door gaps and reveals).
I try to ship a package that makes things easier for our contractors but know full well we are over-delivering without any reward as its all open bid work. Just wondering what others standard is.