The Length of Your Sales Writing

Depends on what you are presenting.

1. Lead generation needs less detail;
    an ad that aims to sell must address every potential objection
2. The higher the price, the longer it takes to justify or create the need.
3. The benefits of an unfamiliar product or service require a lot of explanation
4. The more features, the more writing required.

You have to test the results of your writing using various approaches
to see what works best.

Source: Copyblogger