I've heard that Hideyoshi didn't seriously intend to conquer the Ming and Joseon, and that those campaigns were intended more as a way of nominally fulfilling land claims he'd made to supporters during his previous conquests: "oh, right, I did promise a fiefdom to you. Well, it's over there, you just need to conquer it." If they succeeded, he'd expanded his holdings and fulfilled his obligations; if they failed, they'd be dead or in disgrace.

Not sure I actually believe it, but it's a clever solution and fits with my model of Hideyoshi's personality.

(While we're on the late Sengoku period, Tokugawa Ieyasu stands out as an outstandingly ambitious general that really understood the consolidation thing. The [scary, totalitarian, but stable] dynasty he put in place lasted for 300 years and only cracked once American and British gunships proved that progress outside had caught up with them.)