Money funds do not have the problem of investment duration, because they are risk-free funds. Of course, the longer you hold it, the higher the income.

Bond funds can be said to be as long as possible. After all, they are low-risk. Holding about 80% of bonds can be said as long as possible, but it can't be short-term, and there are still risks in the short term.

Hybrid funds and equity funds are recommended to be no less than 5 years, otherwise the risk is great. More than 5 years, the risk factor is much lower.