There is no “should”, but if you’re saying you have trouble playing certain lines because your current movement is not fast enough, then maybe there is something up with your current movement.
From what I can tell, efficient movements of any kind don’t really have a speed limit, per se. They just get flatter and/or smaller as you go faster, to the point where they get sloppy. If what you are currently doing has a hard speed limit, and that limit is below the point where it gets sloppy, it could mean the movement itself is not as efficient as it could be.
I’d post up a clip and we’ll take a look!
FYI I believe people use the term “directional” picking to refer to economy picking where you combine sweeping and alternate picking. I assume you mean alternate picking with a “single escape” picking motion, where only half the pickstroke pops up above the strings. This is what we’ve called pickslanting, or more generally, a single escape picking motion.