One of the thing I do frequently is making one animation on a skeleton that I later need to preview in multiple locations on a grid but with slight offset in timing. After Effects pre-comp is great for this, but as we has shifted our pipeline more towards Spine I lack an easy way of doing this kind of work. Preferably I only want one skeleton and one animation to tweak, I don't want to duplicate the skeleton to all the grid positions and as soon as I need to tweak the animation I'll have to delete all the copies and redo the whole process which is arduous.
And some times I make longer sequences where an animation repeats at different timings and locations. And some times I have other elements like a waterfall that keeps looping.
I completely understand you have to be elective of your dev time but I dearly which for an ability to create a singular instance of skeleton and or animation, easily tweaked, that later can be played at select times and locations whiteout having to resort to duplicate and delete skeletons and animation over and over. That I why I think an Animation Mixer and perhaps Clones/Instances of skeletons w animations would be a life saver in my kind of work.