"When Three Charms But Four Alarms" was a title of a research paper published a few months ago.
The paper makes the point that in a persuasion setting (e.g. website, banner) more claims are better until the 4th claim at which a consumer sees all claims with skepticism. Hence, the optimal number of positive claims is three.
- • My product is awesome because of X
- • You can even do X
- • Plus, X makes it perfect
- • Wow, I almost forgot that X
- • I wanted to stop but you know it is just toooo good
- • Almost done…
- • Last awesome feature is X
- • I have one more, but I need to go