One of the things that I stumbled across some interesting little appendixes in Original Dungeons & Dragons's Eldritch Wizardry within the Underworld & Wilderness adventures encounter tables.
There were or are any number of rulers or kings that are using humans, clerics, wizards, and others to explore those ruins or wilderness locations astrally or ethereally. And yet for all of the advantages the risks are very dangerous as well. Not only are dungeons & ruins dangerous but gaze of monsters extends far into the other nearby planes. And this doesn't get any easier in outside or wilderness locations. These locations are prime for both other adventurers & rival adventuring parties.
Reading through this collection of early Dr. Strange comic books is the fact that Doctor Strange relied on his astral form for quite a few bits of magical goodness. And it makes me wonder how often human wizards have relied on these abilities to gain an upper hand over both monsters, rival adventurers,& even the occasional cult.