Before changing ad slots after an RPM drop, what segment do you check?

A creator analytics question about checking page, country, device, source, ad coverage, and update timing before changing ad placements.

When RPM drops, I try not to move ad slots first. I check page, country, device, source, ad coverage, and recent content updates before choosing a test. Otherwise one noisy week can become several overlapping experiments. What segment do you check first after an RPM drop?