Don't the micro bosses show up semi-randomly even in surface chunks? I don't play enough to know these intricacies.
They do. Although my experience is that surface areas are sometimes SO long now that you never get to the boss chunks. When an area is 15 chunks long, and the boss is in chunk 8, you'll probably never see it. You can get most everything you need out of a given region within the first few chunks. That's probably going to give you you fill of buildings to explore (unless you're in a swamp chunk on my world, apparently, where I was lucky to find ONE building every 5 chunks) and you'll probably find cave access somewhere in there as well. What reason would you have to keep going deeper?
