Some thoughts after this (yet another) monthly challenge on what makes it possible to make these so fast for me, some points might be helpful for less experienced artists.

1st of all it's obviously experience, I've been doing this for almost 15 years and I no longer have to make stops for "hmm how does an armpit works at this angle if an arm is raised this far up", I've done that so many times it's imprinted already, but even if I had to, I have an archive of references for almost any possible anatomy feature collected over the years.

Same for poses, all of these were pretty simple pinups, and there are also only so much poses that work/look good, and I've done all those many times as well. (Which also always makes me laugh when they go "artist x stole that pose from artist y", unless it was really blatantly traced, artist y didn't invent that pose either and referenced it from somewhere as well) But even at this point I still often prepare some references inbefore, be it pics from pinterest or 3d models set up in roughtly the pose I want (not too precise bc that would take a lot of time I wanna save) and especially for hands.

Same for designs and outfits, spend some time on pinterest/google and prepare a refboard inbefore so you don't have to get distracted for that while drawing.

Another important thing is values. Back in the day I was spending a lot of time overdoing it and adding much more lights and shadows than I should, and that was a lose-lose, not only you make a pic worse, but also spend a lot of time on making it worse.

Another thing about values is value composition, you gotta plan that inbefore, depending on what colors and values does the focal point (character) has and the atmosphere you want. Basically you want the character to stand out and be readable against the surroundings, be it darker char on light bg, or lighter char on dark bg. You are doing it wrong if you turn your pic greyscale and see a grey character blend in with a grey bg. This little diagram shows it well and has changed my life entirely at some point.

Knowing how it all works saves a lot of time later if the pic is a mess and you don't know what to do to fix it.

Having references for values and colors is also great, like an entire board of rito splashes. And last but not least for me is, fighting perfectionism. I always wanna zoom in and work on that little detail over there, polish it and realize you can't even see it when you zoom out. And that is a HUGE timesink. So this time I really focused on zooming in as little as possible, and I draw in 7k resolution.

Obviously if you see the original res and zoom to 100% you can see how messy it is, but resized for web it still looks good overall. And that was hard to accept, like "what if they zoom in and see how it really looks". But yeah, that's what also helped me do these one a day. Now I'm really exausted tho and gotta have a few days off