Catching a falling knife is buying in a downtrend.
Buying a pullback in an uptrend can be done many ways, including scaling in; however, scaling in during the pullback is really only necessary if you're trading large size.
What about the attached example? This is what I mean about my less than stellar ability to pick entries on pullbacks. If I had not scaled in, I would have reduced my overall profit per car by going all-in at the first entry, and taken more heat overall.