Striking a Balance

Much is said about striking a balance in life.
Students are told to balance their time between studies and games. Parents are told to divide their time equally for all the children. Working adults are suppose to balance work with social life. Married couples or parents are told to have time for work, spouse and family. Well said.
Question is at which point is it considered balanced. 50-50, 30-70 or 25-75 and which way should it sway.
An athletic teenager will think that it should be 50-50 but the parents feel that 20-80 is a better choice. A father might want to spend time for the family but what if the boss think otherwise. Even if time is spend on the children, at which point is it right. Too little is the problem most psychologist prefer to think. But if too much attention is given, will the child be too dependent on the parents?
So it is a simple answer to a lot of problem but no one can come up with a well defined formula.