Optimum number of choices for menus/navigation
If on a site, a user needs to put their post into a particular category before they submit, how many choices is too many? What would be the maximum cap before it got confusing?
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Avoid scrolling. That's the only hard rule... if the user can't see some of the choices they may not know it is possible. This is also important because scrolling a drop down works differently on various platforms, and often works very poorly. The drop down list should never be taller than a single screen if you can avoid it.