Raith is pretty on the ball. The key to a REAL GM mode is that you are trying to creative an active story you can change and alter on the fly in order to ENTERTAIN the players.
You aren't trying to beat them, that isn't a GM mode. Sword Coast Legends doesn't really have a GM mode, just what they pass off as one.
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As for "Too highly detailed" why not allow simpler snap in tiles with clear entrances and exits for on the fly and easy construction?
You can have your extremely high detailed large (or small) areas. But we could also have more of a simpler almost lego approach as well.
So you could load up a field, plop down a house... Poof! you could create a dungeon room by room "poof poof poof".
Sure you definitely would get large black spaces if you go for that. Yet the advantage of it is that a GM who uses them can more easily change and modify the layout of the world they build.
