The thing that made me post this is that for whatever reason if I'm lying down or have like just woken up, it usually misinterprets a lot of stuff — I assume because my voice is coming out different. But lately, like the past few days, it's been way more accurate, even when I flub words.
Since the actual voice recognitions happens on Apple servers somewhere, I assume those are getting better as they're trained by millions of people every day.