The concept of compound interest does not mean that you have to buy a fund for 30 years to get compound interest, but that you have to invest continuously for 30 years and have an average return every year, which is compound interest. As for whether to switch every three years, the key is to see whether the fund you have invested in has outperformed.

Problems, income, etc. are obviously lagging behind the market average. If so, then you need to consider changing. But if not, then there is no need to change. The ranking of funds will always take turns to be the winner. You don’t have to pursue funds based on rankings, but consider

Is relative performance acceptable over a period?