In article , Bill wrote:

Doug, Thank you, as always, for your thoughtful answers!

I normally space holes about 2"
apart, but there's no hard-and-fast rule about that.

Do you mean 2" between centers?

It doesn't matter. It's only approximate anyway.

Since "straight-up" is the best way to
exit my subpanel, I wish to be efficient. I've already planned 8 cables
coming out, with others likely to follow. Putting two 10-2 cables in a
3/4" hole and two 12-2 (or 14-2) cables in a 5/8" hole ought to be
efficient! I'll follow the same grouping rules threading the wires
through the wall studs. Lew Hodgett pointed out that threading three
10-2 cables through a 3/4" hole was definitely wrong. I would appreciate
knowing his point of view concerning this.

"Definitely wrong"? Hardly. There's nothing in the Code, AFAIK, that dictates
specific sizes of holes in wood framing for passing cables through. If the
hole is large enough to pass the cables without damaging them, and it's done
"in a neat and workmanlike manner", the Code is satisfied.

Is there any problem with different gauge cables sharing the same hole

None at all.

(I considered that the conduit on the lesser cable might not be adequate
to be next to a hotter cable)? Swingman (smartly) advised me not to do
anything I don't feel confident about--and this is a detail that makes
me hesitate.

My concern was that the location was
where someone might expect to find a light switch (so I would use a
coverplate, or equivalent protection).

Not sure what you mean here.

If I walked through a door and reached around for a switch only to feel
an outlet I would find it a little unnerving. I was thinking of the
types of coverplates that have additional "child-proof" covers over the
outlets or that are designed for exterior use ("spring-loaded" outlet
covers).

Ahh, I see now. There's no Code violation there that I'm aware of. The Code
does require a switch close to the door, though -- the idea is that you
shouldn't have to walk all the way into a dark room to turn on the lights.