User blog comment:MDF infin/Wikia Animations for Mugen:Strategy & Efficiency/@comment-3495717-20141108220812

The new method was primarily meant to tackle characters with overly effects, layered animations, and those that consist of many "parts". It also helps give the reader a sense of what the attack can actually do regarding movements and velocities that are not actually handled within the animation itself, but are instead added to the animation through code (I'd be very surprised if velocity was implemented through the animation in this day and age).

I will always use this method, regardless of how small the animation is, but that's not to say that the other method should be cast aside like NS-4s where to make way for NS-5s (kudos to those who get that reference). As I've said before, either method can be used, though the new one is preferred for the sake of accuracy (and to deal with a common complaint from SPEWGEN regarding a lack of detail on what an attack does).