What resting actually does
Cooking drives moisture outward; resting lets pressure gradients relax and juices reabsorb — slice immediately and the liquid is on the board; rest two hours and it stays in the muscle. Rest length scales with mass: 15 minutes for chicken, 1 hour for ribs, 2–4 for brisket and shoulder.
Building a hold
Wrap the finished cut, insulate it (dry cooler with towels is the classic), or hold in a 150–160°F oven. At 140°F+ it is food-safe for hours; the brisket actually improves through the first two hours of hold as connective tissue continues relaxing. The hold converts timing variance from stress into schedule slack.
The slicing finale
Slice against the grain, 1/4-inch thick, point and flat separately (their grains run perpendicular). The first slice reveals the cook's whole story — smoke ring, bark, rendered fat — and the rested meat keeps its juices on the plate instead of the board. The cook ends at the slice; the calculators just got you there calm.