Very clever ! The technique can be summarized as "using a drill as a substitute for a transfer punch". Transfer punches won't mar the sides of the template holes but drills are always immediately to hand.

OTOH, if the holes are large, a large enough drill may not be to hand. Then one of these...

https://www.amazon.com/Fowler-14-Uni...A1KOS7YF5L52YM

is nice to have around.