Place flour in a bowl. Work in the butter or shortening until crumbs are the size of large peas.
Add 2/3 cup of milk and stir until mixture holds together and leaves the sides of the bowl; add more milk if needed.
Scoop biscuit dough onto a well-floured surface, and fold it over on itself several times, using more flour as needed to prevent sticking.
Roll or pat the dough into a 5" x 8 1/2" rectangle, about 1/2" to 3/4" thick.
Cut biscuits with a sharp, round 2" cutter, dipping the cutter into flour between cuts to reduce sticking. Or cut the rectangle into 12 small rectangular biscuits, which will allow you to skip the step of re-rolling and cutting scraps.
If you've used a round cutter, pat the scraps together, and cut additional biscuits.
Place biscuits on an ungreased baking sheet, leaving 1" between them for crispy biscuits, or barely touching for soft-side biscuits. For higher-rising soft-sided biscuits, place biscuits in an 8" round pan.
Bake for 10 to 14 minutes, or until light golden brown.
Remove from oven, and serve hot.
Cool leftovers completely, wrap airtight, and store at room temperature for several days; freeze for longer storage.
To refresh room-temperature biscuits, place on a baking sheet, tent lightly with foil, and bake in a preheated 350°F oven for 10 to 13 minutes, until heated through.