What is the fundamental challenge in SETI research highlighted by the single, unrepeatable detection of the 6EQUJ5 signal?

The problem of the observational window

The mystery surrounding the Wow! signal underscores the statistical difficulty inherent in the Search for Extraterrestrial Intelligence, specifically referred to as the problem of the observational window. The Big Ear was only able to register the event because, by sheer chance, the signal swept across its narrow receiving beam during the exact 72-second period that the instrument was focused on that specific patch of sky. Since the signal never repeated despite subsequent monitoring attempts, it emphasizes how limited our coverage of the vast observational space is. We are relying on catching a brief, potentially random event precisely when our instrument happens to be listening, making confirmation exceptionally difficult.