By book 4 you should have seen
Dark One stuff
REDACTED BECAUSE I'M NOT SURE IF IT'S BEEN MENTIONED YET
Wolf Stuff (tied into Dreamworld)
Other Matt Stuff
Cursed Dagger Stuff
plus I may be forgetting some
And within those you have different factions doing different things, like the Female power is used and wielded VERY differently by a few different groups to the point that even though it has the same basics, it works completely differently.
In the final books Brandon Sanderson even has a couple character find niche use for old abilities that basically make them into entirely new magics by themselves.
Plus a whole bunch of different factions.
That is not a power in his skill set. You may have misinterpreted or misunderstood some events, but slowing down time is not one of his skills.
I've seen that stuff, but it seems like there still in the process of learning it, they explain a bit more here and there,
and Matt didn't exactly slow down time, but when he was attacked by playing cards he said his perception of time slowed down, the figures in his cards jumped out of the cards they were in, and then everything seemed to slow down to a crawl and he managed to grab knives and throw them accurately
Most of the systems haven't really been explained in great detail yet, I don't know if that happens later or not
the one they explained the most is the female power, they can weave the five elements together to get different effects