your animation file should contain the basics, such as run, walk, crouch, fire. When you inherit from that, you can control in script, like lower half body of bones play run and upper plays fire etc. So no need to have 5 different run animations. One is enough and then you can mix it up with the rest.

I would create left strafe, right strafe, forward and backward for both run and walk. then I would have an idle animation and a fire animation, weapon switch animation etc. Then in script when running and switching weapon, lower body would play run and upper would play switch.

PS: the animation file doesn't need to have any mesh, just the bone structure with the animations.