Moved to DPS forum
Ideally you should design separately for different devices. For example if you intend to publish content on iPad 1/2 (Res 1024*768) and Samsung galaxy Tab Res (1232*752), you would need to have files with different dimensions. If you use a single file for example 1024*768, it would appear in Samsung Galaxy Tab, however would not fit the screen as intended and would result in a poor user experience.
You may use alternate layout feature in Indesign CS6 to design quickly for different devices and then use renditions to publish your content for diferrent devices.