The problem of the exact balancing and overlapping of the good and bad sanskaras is not a mathematical problem of matching equal amounts. If it were purely a question of equal quantities it could be solved solely through the persistent accumulation of the good sanskaras.
For emancipation of consciousness, the good and bad sanskaras have not only to balance each other in strength, but there has to be a point to point overlapping of the one opposite by the other.
So, in a sense, the problem before each center of consciousness is a specific problem relating to the qualitative variety of the nature of accumulated sanskaras.
If the accumulation of good sanskaras proceeds irrespective of the specific constitution of the existing ones, there is a possibility of accumulating in some directions an excess of good sanskaras, side by side with the existence of the bad of a different type.
For example, through self-mortification and severe types of asceticism, some forms of attachment might be annulled; but other forms of attachment may remain untouched by these practices and may continue to exist. The aspirant is not only likely to ignore the forms of attachment that have remained untouched, but he may even carry on further his practices of self-mortification and asceticism by the propelling force of the sanskaras created by these very practices. In such cases an excess of good sanskaras is being created without termination of the limited ego. Even if the other forms of attachment remaining untouched are subsequently undone, the ego can get transferred to these new good sanskaras and continue to live through them.
-Extracted from “Discourses”, 7th Ed, p64