The first time I slept at an inn, I got an event called the Blood Moon, which reset enemies throughout the world. For a bit, I assumed it happened whenever I stayed at an inn. But, then it happened while I was out and about. Okay, so it can happen any time, cool. With more time, it seems to happen every few in-game days.
However, I recently entered the Lake Hylia region, and it happened, like, 3 times in a single 24-hour period. I dunno if it was related, but I was fucking around on the Bridge of Hylia. It almost felt like I was crossing some invisible trigger to cause it, but that doesn't really make sense.
I'm willing to let it go as random luck, but it's still super weird.