How long should an animated banner run?

Web Banner Tip #7 - How long should an animated banner run?
Studies have shown that a typical web surfer spends less than 10 seconds looking at the top of a web page. Thus, a web banner has to display all its content in this time. The call to action, which would usually be in the last frame of an animated banner, should be displayed within this time frame, else the banner loses its efficacy.