Another Graduate Student asked me to talk about my experience on a hiring committee, and especially about the degree to which a candidate should tailor her application materials to each institution.
Other committee members may feel differently, but I think it's absurd to expect first-round applicants to do a significant amount of tailoring. First, it's inhumane: an applicant has other demands on her time, and researching every department in depth, imagining their possible needs and desires, and reworking the already-difficult genre of the job letter 25 or 30 times is not only labor-intensive, but psychologically exhausting--insofar as it requires vividly imagining each place and how one might make a life there.
Second, it's almost certainly time wasted.
Here's the thing: your job letter is, simultaneously, the most important document you'll produce in your job search and a hard document with which to really distinguish yourself. I've read a few catastrophically bad letters from people who genuinely didn't know the conventions of the genre, and a slightly larger but still small number with enough errors or awkwardnesses that it was impossible to take the applicants seriously. But after weeding out the bad letters, the rest sat somewhere on a spectrum from adequate to quite nice; at that point, what mattered most was what the candidates had done and how well they fit our position--not whether their every paragraph was a thing of fire and music.
This, I hope, is good news: your letter just has to get the job done. You don't need to write the world's most eloquent, original letter (in fact, in this context, originality is a bad thing; if someone asks you for a sonnet, you will not be rewarded for your exciting new verse form). You do need to be clear, succinct, and aware of your audience, and your writing should not contain elementary errors. But the conventions are there for a reason: they allow a committee with hundreds of applications to size up each one swiftly, and on more or less the same terms.
Obviously, you shouldn't send exactly the same job letter to every institution, but it's most useful to think in terms of general types of schools. You'll want a few different sentences or even different paragraphs that you can swap in and out depending on a particular department's teaching expectations, and you might emend your wording slightly here and there for similar reasons (e.g., "I would be eager to join [such a distinguished faculty] [a department of committed teacher-scholars] [an institution so dedicated to student success]").
But that kind of semi-generic tailoring should cover most things.* Personally, all I want is evidence that the candidate has read the job ad and has a sense of the kind of school we are (e.g., if the ad mentions comp, your letter should not speak exclusively about the graduate and upper-division courses you're interested in designing). It's probably useful to spend 20 minutes on each hiring department's webpage to flesh out what the job ad tells you--but I wouldn't recommend more than that.
Here's what's definitely labor wasted: showing that you have a detailed knowledge of the ins and outs of our curriculum.
Every department has oddities in its curriculum and its requirements, and it's hard to master them from the outside; it can also be hard to tell, from looking at online course listings, which courses are weirdo one-offs, which are regarded by a particular faculty member as his exclusive property, or which are holdovers from a different era. You don't need to reference our existing course numbers or titles. Just say what kind of courses you've taught or are prepared to teach: surveys, comp, single-author courses A and B, topical courses C and D, and what upper-division or grad classes you might design in the future. With minor adjustments, those things translate into most curricula.
I also think it's generally wasted labor for your letter to name-check existing faculty unless they work in your immediate field or their scholarship really does seem to be in productive conversation with your own; it's worth having a sense of the general profile of any department to which you're applying, but listing a bunch of names is not necessary.
Statements of affinity are nice--that is, remarks about your connection to the region or your interest in the institution's mission ("as a first-generation college student..."; "as a long-time admirer of the Jesuit humanist model of education..."). For my part, I'd say those are agreeable statements to encounter, and I usually remembered them for candidates who got a convention or campus visit, but I don't think they prompted me to give an application a second look if it wasn't strong to begin with. That may be different at other institutions.
As for your vita, it shouldn't require tailoring. As long as it's clearly laid out and easy to read, the committee can find whatever they're looking for. (But seriously, make sure it's clearly laid out.) Think of your vita and your job letter as being in conversation with each other: one allows you to list everything you've ever done; the other gives you a chance to narrate, explain, and reflect on the highlights. Resist the temptation to let either do the other's job.
To sum up: a good letter and an attractive, readable vita are worth laboring over. But there's no need to reinvent them each time. A good letter is a flexible document that you can emend around the edges without--hopefully--driving yourself crazy.
Readers who have served on hiring committees: are my reactions idiosyncratic (or particular to the kind of institution I'm at), or do you generally agree?
*I'm speaking throughout of the differences among four-year institutions, since those are the institutions I know; if I have readers who want to talk about the differences between application letters for four-year and two-year colleges, have at it in comments.