They don't. At least artists are really bad at it when naming their files. I've had to constantly rename assets received from artists to give them some sort of consistency, even after telling them how to name it.

But yeah, Perforce version control is pretty important. It's almost designed to help manage assets, especially large ones. And it's free for under 20 users, I think.

Beyond that, you might want to include the level, screen, and/or date for the assets in your naming structure. Pretty much every company, and sometimes every project, uses a different structure, though.