Fund managers usually don't operate frequently, but they need to do research constantly. Be diligent and investigate more companies.
There are fewer companies that are lazy to investigate. Read newspapers, books, internal reports of brokers and funds, and attend various meetings.
In particular, fund managers of index funds generally only need to imitate the configuration of the market, and then they don't care much.
However, the road of fund managers is not smooth, and they are always under great pressure.