I like how y'all are thinking the complexity was in the web crawling.

It was actually just a simple act of crawling over source files! Amazon was looking to remove their customer support phone numbers from all web pages (to save money, they wanted people to stop calling them; back in the early 2010s)

I share the wonder that it took several days (perhaps that is the anecdote taking a life of its own, perhaps it was actually several hours. Or maybe it was was several days interspersed with on-call support, meetings, and other work running in parallel).

Though.. the file parsing libraries back in the early 2010s in Java are somewhat basic, probably using Java 5. Which does make me wonder, how long would that exercise take in Java 8 or later compared to Java 5?