Why It Doesn't Fail
Steps 2 and 3 are the whole trick. Most crust recipes say "add ice water a tablespoon at a time until the dough just comes together," and that sentence is where pies go wrong. Too little water and the dough cracks when you roll it. Too much water, or too much mixing to fix the cracks, and the flour develops gluten and the crust bakes up tough.
Judy's method takes the guessing out. Half the crumbs get fully wet, into a paste — there's no measuring water because the target is a texture you can see. The other half never touches water directly, so those crumbs stay coated in shortening and bake into the flaky part. Fold the two together and you have a dough that rolls without splitting and bakes tender. It's the same idea behind the old "never fail" shortening crusts, and it's why one handwritten page can be handed to someone who has never made a pie.
Two more details on the card that earn their keep: the metal tin, which heats faster than glass and browns the bottom crust, and the cookie sheet underneath, which catches anything that bubbles over and gives the tin a flat, even surface to sit on. The milk on top is what turns the crust the color you're picturing.