I've been slowly chugging away at my Iron Golems over the past couple days - 5 of 8 done so far. I've been finding that even with a really simple cookie-cutter paint job things go much faster if I paint them one by one start to finish rather than the usual batch method.
For fun I threw together a process post on Twitter, so I'll share here if anyone's interested in the <spooky voice> secrets of Contrast-based NMM </spooky>

My pre-shading base is Grey Seer primer, then a dark-sepia-ish wash (about 1:1:2 VMC smoke, black ink and matt medium, plus about the same amount of water to thin) then a white drybrush. Nuln Oil would probably work too but I'm still a crusty old mix-your-own guy in some ways.

The skin is about a 1:1:2 mix of Guilliman Flesh, Basilicanum Grey and contrast medium, then I hit "chafing areas" with a 1:1 mix of Volupus Pink and contrast medium. (These guys' lore is that, being from the Realm of Metal, they have zero organic materials in their kit...) Contrasts do wet blending really well compared to acrylics because of their slow dry time so it's pretty straightforward to blend it out.

The red bits are Blood Angels Red straight out of the pot, washed with a 1:1 of reddish-brown Gore Grunta Fur and contrast medium to tone down the red and strengthen the shadows a bit.

The gold starts with straight Snakebite Leather, then fairly randomly-placed NMM highlights in VMC Light Yellow and finally spot highlights in white. Those little diagonal slashes seem to go a long way to making (what seems to me) a convincing-ish NMM - you'll see then again in the steel bits.

The steel starts with about 2:1:1 mix of Basilicanum Grey, Talassar Blue and contrast medium (I've found that mixing two colors often bumps the opacity way up with contrasts, so mixing in a bit of medium makes it behave more "contrasty" again), then again semi-random, diagonal-slashy NMM highlights in VMC sky grey then white. A bit of cleanup with dark grey and it's done.
Aside from drying time, this guy took maybe an hour altogether? If my temperament could handle batch painting (or I just had to paint a bunch of models quick, which I don't

) I could probably bash out ten guys to this level in an evening or two without too much trouble.