Thing is Dragon Providence's set times means it's more likely people will be on at the same time to have interesting fights.

With no set times, you need a much larger active player base to have a reliable chance of matching up with somebody any random time you attempt a PvP match. Which is why most "niche" online games I've played with "real" PvP usually have a set time during which it can occur, in order to concentrate everybody together.

I would hope/expect there is some sort of fallback AI opponent (Asynchronous PvP? fighting somebody elses characters but controlled by AI?) if it takes too long to find an actual player doing PvP, or it seems likely it'll be hard to get going. Constantly attempting to do PvP but not finding a match will drop players fast, and the more drop, the harder it will be for remaining players to find a match. (I also assume there's some sort of time-out for turns. Turn based PvP sorta requires that or people can indefinitely stall a match if things aren't going well by simply not taking their turn.)