Cut in the fat in reasonable size batches — say 2-1/2 to 5 lbs of flour at a time, max. Remember, it’s important to keep the fat cold; not to break it into too small pieces, nor to smoosh it into a paste.
Don’t use “bread” flour, use pastry flour. And, if you’re using an extra hard pastry flour like King Arthur, you consider softening it by cutting it with cake flour at a ratio of about 4 King Arthur to 1 cake flour.
Your stated ambitions lay in the area of a 25 lb bag of flour. I’d go about 10 cups of flour (~44 oz) at a time to make a large badge.
You’ll also want to use about 2 tbs salt for each 10 cups of flour.
You’ll want to use about 2/3 as much fat (I prefer vegetable shortening) as flour by weight. Since solid fats like Crisco, lard, and butter are roughly twice as dense as flour that converts to about 1/3 as much fat as flour by volume. So, if you’re doing 10 cups of flour (2-1/2 x 1 quart measures) at a time, that roughly 44 oz translates to roughly 2-3/4 lbs; in turn that means 3 cups of sold shortening which is equal to 3 sticks of butter; and rounds closely enough to 3/8 of a five pound block of lard.
You want to keep the fat very cold through the entire process. Cold fat that isn’t cut too small makes for flaky pastry.
And by the way, “flaky” means that after it’s baked, when it breaks it flat “flakes” — instead of breaking into crumbs. For whatever reason people commonly apply the word to pie crust independent of its meaning. But flaky means flaky, and flaky is a good thing.
Water should be as little as possible and as cold as possible. You’ll probably be somewhere in the neighborhood of 1 cup of ice-cold water per 10 cups flour. **Note that when you do finally bring the dough together, you should clearly see “nuggets” of sold fat in it. If you don’t, you cut the fat in too fine, let it get too warm or both.
P.S. I have not used this recipe, I’ve been told when you add more salt, the flavors come out more. If you enjoyed this recipe, catch the other ones. Try out the other pastry recipes