Eigenvector wrote:
So now that I've punched holes in my walls to fix the galvanized pipes, I'm
wondering what is the most accurate way to repair the drywall.

I cut most of my holes using a punch saw, just jab it in and cut the holes,
but is it more accurate and elegant to use a knife when cleaning those
holes? Also when repairing, is smaller better, that is is the smallest hole
you can cut to clean the drywall the best or is a larger hole easier to work
with?

Next time you cut a hole with a keyhole saw, angle the blade so it's
pointing towards the center of the hole at about a 45 degree angle.
Save the piece and reuse it when you're patching. The angled sides
will keep it from falling into the hole. I use setting type joint
compound, such as Easy Sand by USG, to coat the tapered edges and bed
the joint tape. I try to make the hole smaller than a 8" taping knife,
so my larger knives will cover the patch in one shot.

R