If you don't be patient you'll pay higher prices by buying periodically. Buying perodically is a FOMO act. I'd rather let them go as low as possible. You also have a risk of panicking and selling them again if you buy periodically. Will you really hold them if the crash goes for a week? Probably not.

I think your strategy is not sound during real crashes. It will be good for a one day small crash at it's best.