Good question! (Actually, a reader, BMDela, asked me this. . . so I'm only partially taking credit)
The question was posed thusly:
So, I've been looking for an answer to this question everywhere, and can't seem to find it.
At what point do materials/shaders enter the equation?
Do you put the materials on the master character/props/set, then reference the shaded character into the animation scene?
What's a good workflow for implementing a shading network?
The correct answer is . . . wait for it. . . "It depends!"
Lame, I know, but it's the truth. There are ways to do things that are more 'pipeline' correct and ways that are a bit more user friendly. Some projects work better one way, some the other. So let's look at the two basic ways of doing things. . .
1. Adding shaders to the master files (let's say to the master model files):
Doing this is basically putting your shaders (and their assignment to surfaces) at the front of the pipeline. That is to say, you make your models, uv and texture them completely, then pass them on to rigging, etc. This would seem to be the easiest way to do things and sometimes it is. What are the pros/cons?
PROS: the texture artist only has to apply the shaders once (in theory) no matter how big the show is. Let's say you have a show with 3 characters. The texture artist hits each one and then it doesn't matter whether there are 5 shots or 500, it's the same amount of work for those characters (unless there are changes, which may or may not be a pain in the butt).
CONS: There can definitely be issues with the fact that now all of your shaders are referenced (until you get to the very end of the pipeline). . . but the main problem here is that in heavier scenes you're always pushing around all the textures. When I was animating recently on Skylanders 2, some of the scenes took 3-4 minutes to load, mostly because of the massive amounts of texture files we had to pull over the network. Let's say, as an animation lead touching a lot of shots, I open 20 shots/day. If each shot takes 1 extra minute to load, that's 20 minutes/day. There are 10 leads opening that many shots, so that's 200 min/day to pull textures (that's not counting the 20 other animators who may open 5 shots/day). So over one month, just the animation leads spend ~4000 minutes (or 60+ hours) JUST TO OPEN SHOTS! That's a lot of time/money. And it's not a crazy scenario depending on the shots/network/etc. Might even be conservative . . .
2. The alternative is to push the texturing until closer to the end of the pipeline (after animation):
To be clear here, I'm not saying "don't create your textures until the end", I'm saying "don't assign your textures to the models until the end". So the texture artists would do the same thing as above, they'd just do it "offline" or in files that don't get pushed through rigging and animation. They would then export those textures into appropriate files that just have the textures in them. Then once things are animated, you can just import those textures and assign them to correct objects. Usually you'd want some textures in the master files, things like eyes and stuff that's involved with the rig, and maybe even apply basic color shaders so people can see what's up, but the heavy stuff stays out until after the animators are done.
PROS: Obviously the point here is that you don't have to push around hundred's of MB's of textures for each shot. Work can go much faster down the pipeline. You also avoid the annoying "doubling" of textures (if I reference 5 of the same plants, I end up with 5 copies of the same shader in my scene). You just import what's necessary. You're also doing the final assignments in context so you're making any fixes while you're actually in the scene.
CONS: Mainly that the work scales linearly. So more shots, more work. You can also get some surprises if you haven't seen the textures in action, and you'll see them with less time to fix them.
So the reality is that it depends . . . how heavy are your shots likely to be? How many of them are there? Are the textures integral to the animation or can the shots be animated without them? How rigorous is your pipeline? All theses questions will dictate which is the right way to go!
I've actually been pondering on scripting a system to keep track of what shader is applied to what mesh, etc so the texture artist could save out a file that would reapply the shaders later on down the pipeline automatically. Haven't gotten around to it yet. . . Does anything like this exist? (non-proprietary, obviously)
Anyways, hope that was helpful, let me know if there are any clever things I've missed!