Searching for evidence that someone has actually done the work is relatively efficient. It never fails to astonish me the number of times that everyone believes a particular bit of ground has been thoroughly tread yet, if I try to find concrete evidence that someone has done the work, there is no evidence that anyone actually has. There is a strong cognitive bias (I don't know if it has a name) where everyone assumes that someone else has already tried every obvious or reasonable approach and that belief is treated as factual.