The point of removing the EDP is to get a good contact to strike your weld. So really, you only need to remove a small spot at each weld point to achieve that. However, the edp does burn off around the weld area, exposing bare metal which will oxidize very rapidly. "Apparently" weld-through primers tend to melt rather than burn off, basically sealing the weld in the pinch area. True or false ... maybe someone else can shed some light on this. I've seen a lot of photos of guys who just remove a small patch for each weld. I know for a fact the edp will burn off further than they've removed. Maybe the thinking is the seam sealer will seal out moisture but by the time they apply it it will likely be too late, oxidation will already have started.

Right now I have more faith in the weld through primers. I clean edp off the whole strip where I'm going to plug weld (both pieces) and spray both with weld through primer.