I can spend half a day making a "New" environment. But that is something I am trying to make that is unique and that a player won't look at and go "Oh, I saw that store in XXXX game" I find it oddly disturbing how easy it is for me to spot DAZ Store stock assets now in games... lol.
I kit bash a lot, so I might have an idea for something like a new store. So I will start by looking through what I have or what's available than I will decide on the base (like
MissFortune mentions above) and I will delete or hide anything that makes it look stock. It's like a big game of LEGO to me at this point, as I mix and match and try things. I'll then change shaders and textures to make the scene even more unique.
Once I have base environment down, I will set up the cameras. I've learned that this is super important for my work flow. I lock down about 6 or 8 camera angles and I even track the X,Y,Z positions on a spread sheet, in case I screw up the DUF file later on.
This way, 2 months down the road, when you are coding the final product, and you notice that you missed a shadow or fucked up and have a chair leg half way through the MC's junk, you can just reload the base DUF and spot render the mistake in a minute, rather than having to do the whole render over. One other thing... I NEVER post process the original DAZ PNG's that are generated. They go into an archive that I keep, so when I need to repair a render, i can do a spot render, than layer that spot render on the original PNG from the archive and then I post process that new image for my final product.
Another time killer for me is I like to do custom assets to make my scenes even more unique. Thinks like product labels, T-shirt graphics, Advertising, etc. It's actually really fun to tear apart an asset, load the files into Photoshop and than make new ones for cool effects.
Lighting is, by far, the hardest aspect of scene construction to control. Because you constantly need to adjust it for different poses and applications, so the tips i mentioned above about repairing things and spot renders are harder to do if you have moved the spots around a lot. Usually, I set up the base "scene lighting"... usually picking a dome preset, if there's lots of windows or its outdoors or setting up ghost lights and emissives for an interior scene. Those stay static. For the custom spots, I'll do two sets of renders. One is the base render to lay down the shadows and background, and then I'll render the characters on a transparent background with custom spots to get them the way I like and then layer that on top of the background.
In any case... I've been finding that the hard work at the beginning is paying off later on when I need to go back and add or red-do renders. Once I have the all of the above done, I can usually reload a character sub-set, take 5-10mins to pose them and render right away.
I read another dev (I think) on here who once said something along the lines of .. you can spend hours doing "real" lighting in DAZ but is a PITA. It's so much easier to fake it with other techniques. Heavily paraphrased.