Firstly, to understand the responsibility of a production artist, let us look at what the overall game production involves.
//////// GAME PRODUCTION ////////
Unlike a typical illustration or mood concept, a production design is the process of coming up with a new character, according to a initial brief, and developing the concept alongside the client and cumulatively through multiple iterations come up with various versions and the end result design.
Game production is rarely a one hit wonder type of concept (to make a really, REALLY good functional believable character)
//////// GAME PRODUCTION DESIGN ////////
Designs can have multiple phases.
In the initial instance, a vertical slice demo is typical of game development. This means conceptualizing a bunch of characters to explore mood/feel of a new game or new sequel.
Prior to developing a VSD, you will need to develop some concepts to explore the mood and feel.
//////// PRE PRE-PRODUCTION ////////
You can call this Design - Line 1(also know as blue sky thinking. no known script is made and the art team often get time to just draw anything, throw ideas about and produce interesting stuff. Once a few piece of artwork start to develop some sort of early identity, a project idea comes together)
//////// THE PITCH ////////
OK, you have some artwork, but now you need to get permission to pitch this idea so the game has a chance of being funded to produce a Proof of concept. This is important, as it either dies a silent death, or has some potential to be funded into a demo.
The demo can also sometimes be called a vertical slice demo (a snapshot of what a segment of a game may look like in gameplay, looks, feel, environment and these are often shown at various game conventions and such). Often, the overall game is not finished and you may find that teams spend effort to build a demo but this build may not be integrated in the game overall - due to the typical nature of the beast that marketing tells you, you have 2 weeks to show the game build to the HQ, to some press, etc
There are HOLES, and one has to do the best to make it look good. These additional information is important so that you as the concept artist are aware of what your responsibilities, roles and job lie - and thus how you can help out.
If stuck for time, companies then look at visual outsourcing of promotional material, design and such. 3D base models and textures are nowadays outsourced 90%, freeing up the core team to tweak, provide quality assurance and refined the base models
Once you have these, you can subsequently have a initial model produced to walk within your crude demo. Further feedback and development will produce a Design - Line 2
//////// Early DEMO ////////
At this point, we skip forward 2-3 months of development time and you start to show your internal team/publisher the early Demo (milestone1)
There will be high poly tweaks and reams and reams of emails/feedback on the environments, characters, props, AI, early gameplay and so forth. If you are lucky, your final design - line 3 will be the representative design for the early VSD.
//////// GREENLIGHT. GO GO GO! ////////
If favorable, your early demo gets greenlit for production.
The early designs can be used as a springboard for the new project title.
Often, the designs may die a silent death, or be redesigns another 3-6 times, with each tweak being more and more subtle. Large productions will have focus groups, metrics and critique from just about everyone including the local window cleaner (joking). But it will feel like that.
From now till final production, the character designs may undergo some minor changes or if they are the main characters undergo more changes. This can prove a bit frustrating, but is fairly normal for various game projects. Especially large established franchised. Such, is the nature of the beast.
A mature artist, understands these and sometimes there is nothing for it but to produce version 1-50 each month.
You have to be a big boy/gal to take on such a responsibility. Unlike illustration, your job is to be the most perfect production artist (cog) in the overall game production process (wheel).
Such lies the challenge.
And the just rewards!