A key is a secret you carry for thirty years. It is also a piece of metal that has to be cut by a wheel, copied by a teenager at a hardware counter, and turned in the dark while you are holding groceries. Each of those costs entropy. Drag the cuts and watch the keyspace.
MACS is the biggest jump allowed between
neighbouring cuts. It is not a policy — it falls out of the cutter geometry:
MACS = (pin spacing − cut root) / (depth increment × tan(cut angle/2)).
Exceed it and the blade cannot lift one pin without dragging its neighbour.
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The curve is the entropy a lock family gives up to MACS at the current pin count and depth count. For Schlage's 10 depths, MACS 7 is a famously loose constraint — it forbids only the adjacent pairs 0–8, 0–9 and 1–9, three of the 45 possible pairs. For Kwikset's shallower, closer-spaced cuts it bites harder.
Specifications are from locksmith trade references, listed in the post. Counts here are exact (a dynamic program over admissible bitting sequences), not estimates. What they are not is a measure of how hard a lock is to open: picking, bumping, shimming and simply unscrewing the cylinder all ignore the keyspace entirely. This page counts the secret, not the security.