Only top 20 HW scores count towards the global ranking, so if you have 20 results worth 1-2-3...19-20 boints, and then get another score worth 21 boints on a piece of HW you haven't benched before, then the score worth 1 boint won't count any more, so your increase will be 21-1=20 boints for the GLOBAL ranking (for hw masters you will gain the full 21 boints), as your top 20 HW scores will now be 2-3-4...20-21.