I don't have enough money to buy heavily into dumps. What I do is choose a dollar amount, let's say $500, for example. Then if the value drops below $500 to $495, then I'll buy $5 to top it up to $500 again. If it gains, I don't do anything, only if it drops below the value.
The dollar value of my crypto is the heuristic for measuring how much to buy during a dip.