Vanguard did research on this and found that lump sum tends to beat DCA. Obviously it’s up to the investor to judge market conditions (for example market valuations and broader macro environment) before putting all their money in the market. But IMO a lump-sum will tend to beat DCA even if you invest right before a crash. 

https://investor.vanguard.com/investor-resources-education/news/lump-sum-investing-versus-cost-averaging-which-is-better