Making a slight improvement to a small system produces a small benefit. You will experience a small benefit just by adding one good habit to your life.
Making a slight improvement to a large system amplifies its benefits. The addition of just one positive habit to your life, which has many other positive habits, forms a gestalt that will improve the rest of your positive habits.
A musician who only has one song in his repertoire doesn't gain much attention from releasing one new album. But, a musician with a lot of albums can get a lot of attention just by releasing a single.