UI guidelines are often too general.  On the one hand, to be guidelines they must be somewhat general. While designing an application visual consistency can be helpful。

Consistency in other elements can make it easier for users to transfer skills when learning different applications.  Specific UI guidelines help maintain consistency across different products。

• Useablity means user------

Is easy leaning

Is efficient to use

Provide quick recovery from errors

Is easy to remember

Is enjoy to use

Is visially is pleasuring