Is there a UseCase for Snap to Volume? By now, I have probably tried every snap-setting that Blender has to offer. I can say that most of them are truly useful. But for the life of me, I cannot figure out a possible use for the Snap to Volume Option. 
Sure I have read the documentation which tells me that: 


  Volume
  Snaps to regions within the volume of the first Object found below the mouse cursor. Unlike the other options, this one controls the depth (i.e. Z coordinates in current view space) of the transformed element. By toggling the button that appears to the right of the snap target menu (see below), target objects will be considered as a whole when determining the volume center.


Still, what could that possibly be good for? I am completely stumped! 
If you know, please educate me.
It's very useful for rigging. Most of the time before the actual rigging you would want your rig bones inside mesh (probably around the center), but actually getting bones inside could be a problem that often requires moving around ortho views and dragging bones on 1 axis at at a time. With this snapping you can select joint and snap it to around the center  of arm or leg, do it for other joints, fix rotation and that's about it. Thought it doesn't work that well with complex shapes like hips or shoulders.