I have done a post in the past discussing how after a massive rally, if price makes a 2 legged pullback where second leg breaches first leg, the pullback tends to end around 75% extension level of the first leg.
If instead the pullback is a AB=CD or 1 to 1, I would start to consider it as a steep pullback and stay out.
However if price ceases to drop further it might signify a good buying point.