The touchtennis rankings are based on a 52 week revolving system. Only your top 8 results will count towards your rankings. However if you only play 7 events then you are given a "zero pointer" for one event and this can dramatically affect your ranking calculation downwards. In order to see how many tournaments make up a players ranking, simply click on their profile and look at their Official Ranking tab to see their progression as well as their Ranking Calculation.