I'm conducting some research to help with a personal project. I am interested to know your personal preference when working with animation source files. If you don't directly work with them, feel free to answer for which method your colleague or studio uses.
This next part isn't necessary for my research but I would also be interested in a short explanation of why you do it the way you do it, whether it be personal preference, efficiency reasons, tool integration, you've been doing it that way since forever, etc. Maybe it'll spur some interesting conversation.
Thanks guys!

Replies
So, i'am working in a project where the main character will have a lot of guns and wearables (boots, legs, gloves, hats, etc).
Since each gun will have a different animation, like reloading and the way the character holds it, i gonna make every animation in a separated file, and split lower body animations from upper body animations, then we gonna merge the two parts in the game.
So whenever we want to tweak an animation or add a new gun, we just need to open that animation or create a new one from the base character.
If we use Maya we usually reference the master rig. So any rig updates are automatically updated.
EDIT: humm i found this -> http://www.3dfiggins.com/writeups/mayaReference/
I've never tried referencing a rig though. Has anyone tried that in max?
Need to tweak the rig ? No problem, all animations will be working after the edit. Simple as that. And for us that work with animation in separated files. You just need to tweak the rig once in one particular file and done.
@Bruno, There is no referencing in Max for animation. xRefs are lame, and can't be animated. But with Biped's BIPs and saving XAF files it's easy enought to transfer anims. To an updated rig.
@Bartalon, in general it's just easier to work with for characters. If I'm working on a simple object like an unmanned Turret or an animated building, I'll do it all in one file.