Game concept
Existing Development
From the game's encyclopedia
The Increase Development in County steward task suffers from diminishing returns. The more Development a County already has, the more Development Growth is penalized.
By default, Counties reach the maximum Existing Development penalty at 10 Development. Each Era has an Innovation which significantly increases this limit, going all the way up to 90 Development in the Late Medieval Era.
Innovations that affect the Existing Development modifier:
• Public Works
• Communal Government
• Urbanization
• Renaissance Thought
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Existing Development is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "The Increase Development in County steward task suffers from diminishing returns." Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.