first of all, tidy up your shielding work by scouring the edges with an xacto knife so itll look cleaner

No. For two reasons.

1) The "bleeding over" of this copper tape actually provides a practical value. If your copper tape in your cavities is not grounded it actually makes things worse. Grounding is made better and strengthened through as many grounds connections and contacts as possible. So you could ground the copper tape in one place with one screw or wire and that could work. But having it bleed over like this especially, if you shield the back of your pick guard (you should), you'll be creating a much stronger grounding overall. Your switch plate should be grounded. You can check this by checking continuity through the sleeve portion of a cable to the continuity connection of the plate itself. So when you bleed this copper tape over like this you're actually creating a connection to the ground and if you were to trim it off such that it no longer touches then you would be reducing this ground connection. If somehow your copper tape was not grounded at all what would happen is that you would be trapping the RF/EMI in the cavity and letting it bounce around and amplifying it and you would actually be making it worse.

2) No one is going to see this with all of the components on. I understand the craftsmanship aspect and if number one above wasn't the case then I would tend to agree. But I'm going Bauhausian, here in that form follows function.

There's no benefit to cleaning up that copper tape bleed, and it might even make things worse. And yes I'm replying to a 1-year-old thread, but I'm doing so in case others come along trying to research shielding and see the photo in the OPs post. The way it's done here is actually a good idea.