Structures tend to spawn in groups

Structures tend to spawn in groups. I mean that it usually happens that you can't find a certain structure while traveling for hundreds of blocks, until you find 2 or 3 of them in a few adjacent chunks.

And this isn't just a coincidence, it happens very often with all structures (while it doesn't for the vanilla ones).

For example, an user playing Hodge-Podge III said he wasn't able to find a structure. I made a creative world and couldn't find them for a while too, until I found this:

(and there even are one or two more near that I didn't catch in the screenshot)

Sometimes it even happens that big structures generate so near that one overwrites the second, like it happened here in RaolCraft:

This castle is supposed to not be accesible until the player can find a key for opening the door, but if it generates this way then players could just bypass the quest for the key...

If you find a solution to it, you could make an option to enable this kind of generation because, while it would be weird for structures inhabitated by important NPCs or bosses, it would be useful for custom trees and similar.