About using these schemes in statistics: there is a post by @TimeKnight ( Delve's Statistic ) that shows average values of chest upgrade chances and treasure multipliers. I improved this approach and calculated these parameters for known factions, you can see results in a GoogleCalc sheet: Delves Effectiveness - Google Sheets . They may answer some questions, like “why City of Thieves is so good” or “why Duergaroth is nothing special”. Figures presented in the sheet can be not very exact due to a general approach, without deep examining all possible combinations of rooms in delves.
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