Shelfwalking
There's truth both to Julios Alves' essay on the power of "walking the shelves" and to libraran mbelvadi's comments on same. On the one hand, for many academics, idly browsing the shelves has been (and probably will continue to be) the source of many an intellectual spark. (Scanning journals on the shelves performs a similar function.) And, of course, electronic searches, even in fulltext databases, pose all sorts of potential issues: sources missed because of wonky metadata or OCR, someone not using/misusing a keyword, the user not knowing the keywords, etc. On the other hand, as mbelvadi points out, shelfwalking's randomness, as well as its necessary spatial constraints, mitigates its usefulness as part of an undergraduate's--or graduate's--research program. This randomness, though, extends beyond catalog classifications. For shelfwalking to work, the walker needs to have some kind of intellectual framework that can organize the finds. The graduate student of Alves' imagination may have acquired sufficient background knowledge to recognize that those texts are worth looking at, that these issues are important to the scholarly conversation, and so on. But then again, the student may not, especially if they aren't already acquainted with the kinds of academic vocabulary in play. This is even more likely the case if the student is an undergraduate (let alone a lower-division undergraduate), and not particularly invested in the discipline.
By the same token, shelfwalking doesn't necessarily offer up any revelations when the texts in question are primary rather than secondary. The University of Chicago, for example, has (or used to have) a lot of Victorian etiquette manuals and domestic advice books out on the shelves in the Regenstein Library; OK, but what do you do with them? Someone with a fair amount of background in Victorian class formations, debates about domesticity and gender roles, etc., should be able to productively formulate questions about such books that "activate" them, as it were, as opposed to relegating them to permanently accumulating dust on the shelf, unopened. But you usually need to know something before you can recognize, at random, something else that needs to be known.