It goes both ways not only just for cinematic sequences but can be used for gameplay motions as well, so if you really want to get the anims as well as they could be, you will be relying on keyframe animation for every motion clip of your animation. For instance character jumps and lands, those two animation clips already coming in from Max/Maya will not only have the body motions but also jump and land animations for the hair, which is also keyframed. Same with walk loop, run etc… This gets you to rely less on unpredictable and most of the time bad looking realtime sims on hair or even cloth (but thats another topic) and to rely more on hand animation and pre-bake motions for these parts. This process is no doubt the most time consuming and would require more experience and solid workflow, but for polished games with good hero characters and naratives/combat this would be in my opinion the best approach that would produce from a visual/art side the best looking results.