That is the theory but not always the case for many funds and they have to other funds to keep their returns high,given that super is relatively new many funds have few retiree's Australian super has less than 10% of their members are on pensions ,it will take until funds have been going for forty years before we get the balance between retiring and new members and some will take lump sums and part lump sums. I have been taking 5% a years from my fund for 8 years and have been able to get double digit returns every year apart from one year,a small fund can achieve this but big funds will end up getting single returns in the future.
