The Long And Short of Copywriting
Products or services that are popularly considered "dry" (e.g., banking services) generally should have short copy. Similarly, copy directed at busy people such as professionals mostly should be short. They don't have time to wade through pages of copy.
Useful techniques for short copy include a brief letter making major points, accompanied by an enclosure such as a fact sheet, flyer or brochure. A recent solicitation for a Visa card from Providian Financial included a good, short letter with the headline "No Annual Fee," certainly a major selling point. Subheads make the other major points and are followed by brief amplifications. A brochure also mentions more of the card's benefits.
The information needed to make a decision is all there in a compact package.
When to use longer text
Of course, many situations call for longer text, such as a mailer touting or soliciting:
* magazine subscriptions or book club memberships, because they're targeted to people who like to read;
* high-involvement items, such as health products or investment newsletters, because people interested in such things want, and often need, a lot of information;
* products used for special interests, such as car repair or golf—things about which prospects may like to learn more;
* charitable donations; letters for a good cause can offer one compelling anecdote after another.
For multiple-page letters, with pages joined along a vertical fold, an odd number of pages are preferable, because the sales close will fall on the right side where it's more likely to be noticed.
There are examples of good copywriting, however, where this isn't done. Looking at an American Association of Retired Persons' package I see the copywriter cleverly put closes on both page three and page four. The close of the letter's body is at the bottom of page three, and the P.S. is on page four. This might help the chances of connecting with someone who is just scanning the letter.