I'd run it across the entire site. Sure, we do have logs, but it's not easy to access them for all *.yahoo.com. Logs from each property are ingested into different places. The infrastructure is way more complex than it should be making bare-minimum monitoring like alerts on non-200 responses on all properties difficult to maintain.

Each property has their logs ingested, indexed, and archived differently. I only have access to my little arm of the company infrastructure. Logs should be monitored properly by the responsible owners of each property (or in a more sensible way), but unfortunately this is not the case... :)