Most status effects wear off following the third turn of the target which gets them, although some (such as Invoke and Rush, and obviously Turn Stolen), use a different number, and sleep/stone/confuse are just completely random.
This guide has the complete list. </shameless plug>
Widespread is ridiculously good (and is a large part of what makes Heal so good), but it's balanced by being stuck in a class with crappy stats unless you invest about half the game's worth of CSP into it. Sacred Slayer OC is too strong overall regardless, though.
Star Ocean 4 - Aeos revisit. Both boss fights here are so good, swarm fight done right then nasty boss who summons minions and encourages you to switch between PCs to deal with them or the boss most effectively. I've found the game kinda easy for a Star Ocean thus far, though much of that is the fact that it's kind of a replay in practice due to watching everything before (or maybe it's just a comparison with Dark Souls), those fights were seriously intense though. Great stuff. I'm definitely on the Captain K train for this game.
Dark Souls - So Iron Golem went from "this is frustrating it's kind of a long fight and sooner or later I make a dumb mistake and either fall off the cliff or get hit by his ridiculously strong grab attack" to discovering that the 2-handed heavy attack from my halberd all but stun-locks the guy. Um, lol? (Funnilly enough I only started using it because my light attack sometimes missed between his legs and that got frustrating.) Anyway I made friends with some demons who can now ferry me back and forth to some swank castle. Sure whatevs.