This is a great question! I've been thinking about this question a lot lately because I keep being asked about it. In short, I think someone who planned to invest x percent in equities should continue to invest x percent in equities regardless of current CD rates. This is my opinion given that you don't know what days are going to be the big market jumps, and you don't want to miss them. Here is data to backup what happens when you just miss a few days
https://www.fool.com/investing/2019/04/11/what-happens-when-you-miss-the-best-days-in-the-st.aspx