To understand the law of compounding applied to habits, please read the below insight.
This insight inspired from Atomic Habits by James Clear makes it clear how habits follow the law of compounding and hence beyond a threshold lead to non linear benefits.
Our brain’s working memory like a computer’s RAM is of limited capacity.
Though there is still dispute on maximum number of items that can be kept in working memory at one time , the number 4 is the mostly accepted number.
This being said a lot of the great personalities can efficiently multi task for top performance.
How this is done is through rigorous practice , to convert mundane work into routines that become habit patterns in the basal ganglia.
Habits do not occupy the conscious mind and can operative out of our subconscious mind , thus enabling efficient multi tasking by tricking the brain.