Strunk and White call it “pitchman’s jargon”. Bryan A. Garner describes the phrase in his Modern American Usage as “trite” and recommends avoiding it.
“Each and every” is one of my pet peeves, and it jostles for position at the top of my list of most annoying ’emphasizers’ that are now ubiquitous in marketing and media hype. (“First ever” is at Number 1, and will probably stay there for the foreseeable future.)
“Each and every” is tautologous, even though the words have slightly different meanings – or perhaps more accurately, different emphases. Each means every one separately, with the emphasis being on the separate identity of each person or thing in the collection. Every means each and all – without exception. Here the emphasis is on the fact that everyone or everything in the group has something in common. Take these two sentences: “Each camper carried his own lunch.” “Every camper carried his lunch.” The first sentence is pointing out that the campers had a separate meal each, probably lovingly prepared by a doting parent, and each had responsibility for carrying his own brown bag. In the second sentence, the thrust of the message is that all the campers were carrying their midday meals; no-one was going hungry on that particular day. Even though the same campers were carrying the same lunches in the two sentences, their meanings are subtly different.
“Each day brought a different challenge to her project, but every day started with a cup of coffee.” In this case the challenge gave each day its own unique and particular character; the coffee united the days and described a homogenous blur of caffeinated waking hours.
“Each and every” has slowly but surely crept into marketing- and media-speak as a way of emphasizing the no-exception, all-inclusive nature of an offer, deal, or campaign, or even just emphasizing a fact. Here the emphasis is clearly on every thing, every one, every time. Each is like a toddler being dragged along behind with a thumb in her mouth: there’s no place for individuality or separation here. Using the phrase “each and every” is really a form of literary impotence or laziness, where more creative wording could be used to give every the weight it probably deserves. Merriam-Webster’s Dictionary of English Usage notes that usage experts generally denounce the phrase as a cliché, a pomposity, and a bit of bureaucratic bombast.
The same criticisms can be aimed at the similarly tautologous phrase “first ever”, another marketing-hype term, which tries clumsily to accentuate the first. There are no different gradations of first: something is either first or it isn’t (when it’s second, or third, etc. …). Adding ever doesn’t make it more first; it serves only to annoy – and possibly even to raise the suspicions of – the attentive reader or listener. A more elegant way to underline the fact that the person or thing in question has beaten everyone or everything else to the start-line is to introduce a qualifying verbal phrase using ever as an adverb: “The first person ever to set foot on Mars”; “the first time the piece has ever been performed”.