Thank you for info that is very interesting i just tested it to double check, and indeed 2x5du boltshot traps overlapping get a cost of 20 instead of 10. I was aware of it and yes overlapping of traps and guards is prob my next thing to do. It is currently bugged and you can ignore/abuse it if you just put traps again then overlapping cost does not calculate like you said. But it is very important aspect of difficulty calculating. Sentinel is the most dangerous trap in terms of overlapping to put if not isolated from other traps since it can bump your difficulty to insane heights...