It's not about doing a lot of races to get points, it's about the quality of the field and your place in it in whichever races you do. As a crude example, if you win the national 25 championship, you'll be higher in the rankings than somebody who wins several local open 25s, because beating all the best short distance testers in the country once trumps beating your local competitors every week if none of them is rated in the top 10 nationally.
It's not about doing a lot of races to get points, it's about the quality of the field and your place in it in whichever races you do. As a crude example, if you win the national 25 championship, you'll be higher in the rankings than somebody who wins several local open 25s, because beating all the best short distance testers in the country once trumps beating your local competitors every week if none of them is rated in the top 10 nationally.