Yeah I think that kind of thing isn't supposed to be "predictive". The "rules" in series aren't very clear, sometimes they type stuff out into a keyboard, sometimes they connect a cable from their head, sometimes they just pass stuff around/hack basically just just "telepathically" without even needing the wire, they do whatever seems cool for a scene. I think the "splitting fingers" thing happens in one of the movies but also in SAC, but I think the point is just that it looks interesting and seeing the fingers do that and start suddenly typing quickly gives a sense of tension/urgency that you wouldn't get if it was just the character sitting back and staring at the screen (even if "in universe" they're able to work just as effectively that way)