Campaign tolerance is the restriction you place on how much the campaign spend and budget by channel can be altered and optimised by the machine learning model toward where the optimum attention performance is predicted to occur.
This tolerance is dictated by assigning a plan tolerance of a low, medium, or high value. A low tolerance will set a 10% limit on optimised spend, medium will set 30% and a high tolerance allows for a 50% differential to the campaign budget allocation toward where the machine learning data determines is most suited.