Exercise 1: Time Machine and Chapter 7's Snapshot Mechanism — Possible Solution
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HOW TIME MACHINE RELIES ON APFS SNAPSHOTS
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Per this chapter, on APFS-formatted destinations Time Machine's actual mechanism IS the copy-on-write snapshot system Chapter 7 already explained. Local hourly snapshots are kept on the internal drive itself regardless of whether a backup disk is connected, and those same snapshots are what get replicated outward to the backup destination once one becomes available - Time Machine isn't a separate backup technology layered on top of APFS, it's APFS's own snapshot feature applied specifically for backup purposes.

WHY THIS MEANS MORE RESTORE POINTS IN THE SAME SPACE
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Because copy-on-write snapshots only need to store the blocks that actually changed since the previous snapshot - not a full duplicate of everything - each additional restore point after the first full backup consumes only as much extra space as the actual changes require. A series of full copies, by contrast, would consume roughly the full size of the data being backed up every single time, meaning far fewer restore points could fit in the same total disk space.

WHY THIS WORKS AS AN ANSWER
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It correctly identifies Time Machine's local snapshots as a direct application of Chapter 7's own APFS copy-on-write mechanism rather than a separate technology, and correctly explains that storing only changed blocks (rather than full copies) is specifically what allows many more restore points to fit in the same amount of disk space.