Game concept
Grace
From the game's encyclopedia
Most Schemes have a grace period of around ~6 months before they can be discovered monthly.
After the grace period is over, Schemes may be discovered monthly, causing a Breach. This is at a far reduced rate than when the scheme is executed, but checked significantly more frequently.
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.
Grace is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Most Schemes have a grace period of around ~6 months before they can be discovered monthly." It is part of Secrecy. 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.