I like to use the shape manager with multiple shapes hooked to controllers, or parameter sliders (blend two shapes with a parameter slider left to right, eg.) to later be saved with stored animations in clips in the mixer. I then play with clip animation later only, with layered expression/parameter key frames, not touching the shape manager... Another example, link teeth to a lip shape for a mouth phoneme expression. Once I have that, save that as an animation clip and do the lipsync with that clip in the mixer. I extensively use the animation mixer. I have little idea how ICE works, but I need more time to study it. I’ve only been in Softimage like 2 year, mostly self taught... but being a bit OCD with how you program your clips and shape information in expressions then animation clips certainly helps. I usually save my clips externally and use Windows explorer to call them when I need them.
I’m here to learn though, still a noob in these things I think.