Crawl tools love a big number. Pages discovered, URLs in the index, requests per day. Inventory is not the same as a change history. You can know every URL and still not know which of last month’s edits is showing up in traffic.
A change calendar has to hold the delta: what was true on the page last week versus this week, and when that delta went live. Index size is a backdrop. The plot is the edit.
If your stack can tell you how many pages you have and cannot tell you what changed on them, you bought a warehouse, not a memory.