Fred wrote:

Thank God for caulk and paint.

Non of the inside or outside corners of my walls are true 90 degrees so
final results at the corners are a little off when mitering at 45 degrees.
Even off by 2 or 3 degrees will show up as out of alignment at the corners
where the baseboards don't meet exactly. I've tried coping for the first
time but it was a long process with trial errors before it looked ok -
forgot to take the coping saw with me, had to freehand on the TS. I had
some odd shaped walls also and had to divide the angle exactly by half
using trial and error or simple high school geometry as eyeballing it
results in disaster. After about four hundred feet of baseboards I'm
getting the hang of it so accurately is a must since a degree off here and
a 1/16" off their will show. So far this is only simple angles and I
needed to resort to caulk and paint.

Next crown moldings with compound angles - now I'll be really challenged
with those funky walls. I need to dust off my descriptive geometry book
and see if it helps. Is this where coping comes in play more than
baseboards?
Every person I know that has ever done wallpaper "professionally", has
stated (flooring people make the same comment) "if they ever find a house
with a true 90 degree corner", they will buy it!