In most cases, we started little or nothing in a retirement account. DAC is very powerful in this case. In a lot of cases, it can beat S&P.
However, when your account grows to certain level (10+ x of your annual contribution), your contribution can only buy small amount (less percentage) comparing your holdings. Then the market up/down have huge impact on your return. Then we need to pay attention to the market and avoid the big dip when the risk is high (like now).