Broad index funds are indeed recommended to be held for a very long time for maximum yield. Continuous investment over at least 15 years is better precisely bec

Broad index funds are indeed recommended to be held for a very long time for maximum yield. Continuous investment over at least 15 years is better precisely because it spans multiple business cycles and allows taking advantage of the lower prices during dips and recessions. But that's completely fine for those that want to save up for retirement.