Does a dust jacket's style indicate anything?

You can use a dust jacket style and—for the non-giant issues—approximate size to broadly date the era of the dust jacket (and likely the book it covers). For example, the spines of Boni-Liveright dust jackets from 1923 to 1925 had the logo of a monk at a writing desk, titles printed from 1929 to 1932 usually had the legend "Books that have something to say to the Modern Mind" near the top of the back panel, and the 6.5" tall issues from the 1930's often had wonderfully imaginative pictorial front panels.

For a nearly complete collection of illustrated examples with lots of detailed information, see Quick Guide to Regular Dust Jacket Backs 1917-1974 and Quick Guide to Giant Dust Jacket Backs 1931-1974.

---