Hoping any of the comic book historian fans (or people in the know) might be able to answer this one.  In the Jack Kirby Artist Edition thread, there was mention that some of the pages were "twice up" artwork.  

I was reading an article here:

http://www.artofthecomicbook.com/history/art-reduction.htm

and it says "Like publishers of magazines and newspapers, comic book companies didn't regulate artist's working preferences. Judging from Golden Age and Silver Age originals, the most popular production art size was 12 1/2" x 18 1/2" (also called "double up"). As long as artists adhered to the 2/3 ratio of the printed live art zone of 6" x 9", editors didn't care how big the art boards were."

My question: why would an artist choose to work on a "twice up" board?  I would think a double-up size would be WAY more work?  And if the rate is the same, it's more work for the same money?  (My understanding what that page rates were not great in the "olden days", so any legitimate reason to not kill yourself at the art board would be a good thing I would think?)

Thanks in advance!

I've self-published a bunch of comics, I've had a couple of jobs for smaller publishers, and I've done a lot of smaller size giveaway comics for a specialty publisher--and I've also experimented just for fun.

Smaller is quicker and easier, but mistakes are more obvious.  Figures are easier to do smaller, but backgrounds turn out to be easier the larger you go.  If you can ink with a fine point, smaller is okay, but if you use brushes or thicker pens, then bigger is the way to go.

Most of the giveaway comics I've done were published at about 4 x 7 inches.  The first one I did, the original art was 11 x 17 in., but with the follow-ups I did the originals at pretty much printed comic size (on 8.5 x 11 sheets).  So, the lines on the first one were reduced quite a bit for print, and it turned out really nice!  Fine lines always look great!  But it was somewhat wasted effort.  The later ones were smaller and therefore reduced less, but turned out just fine for that size.  After my experimentation, I can always tell when a name pro has either switched to smaller originals or switched to thicker pens or brushes.

Compare 60's Ditko to 80's Ditko--a great example  His early SPIDER-MAN was printed with a lot of fine lines and heavy detail in the buildings, etc.  His later work had thicker lines and less detail--he either switched paper or switched pens/brushes.  Sometimes, these changes come down to an artist just getting older and can't see quite as well.  In that case, it would be nice to still have the option of working twice up, but photocopiers and scanners that can fit that size are hard to find.  (Do the pros still send in original artwork?  I have to imagine it all gets emailed in or dropboxed now.)

So, basically, if I want (or need) to be messy, working at a larger size hides that messiness better.  But working smaller or larger might end up being the same amount of work--it's just whatever the individual artist is more comfortable with.