I generally do it by feel, partly because I'm treating "value" somewhat subjectively, something like "intellectual value" or "scholarly value" rather than "numb

I generally do it by feel, partly because I'm treating "value" somewhat subjectively, something like "intellectual value" or "scholarly value" rather than "number of hits". So I look for things that Wikipedians don't seem to be spending a lot of effort on, but which imo a good encyclopedia should cover.