It differs a lot from company to company. If its a big company they usually have complex pipe line. smaller companies tend to let you do a wider range of work.
From my own experience with TV-ads there are a wide range of pipeline approaches.
If i get to choose how i work, i lean more to the bigger pipes. They let me concentrate on my best skills.
Usually i get so called “Assets” from the people doing modeling, texturing, simulations and animation. I import references of geometry that if needed i apply animation cashes onto. That give me clean a scene to begin working with.
If there are any textures made when i pick up geometry, the texture artist has already attached them to the geometry shape nodes. That way my shaders pick them up automatically. No need browsing around the network or asking people for the assets i need.
When i have a basic lighting setup of my scene i ad a grayshaded and one textured render to that days dailies. parallel to the lighting and shading in Maya i have a comp made for each of my shots. when a shot is done all the important comp nodes get exported to the real composite people so that they can make the final tweaks and coloring and make a nice timeline of the ad.
all versioning of assets, scene’s and other stuff are done by the pipeline tools that handle all the data. so we don’t need to searching for stuff in folder manually to often.
To brake it all down. I do lighting and a simple comp. that’s it. If something unexpected happens i yell or send a message to the person responsible for the fault.
At smaller companies you the artist has to solve more problems and error by yourself, taking time from you actual job.
Hope that answered some of your questions?
//Stefan