We need to write customer-centrically, so I would value ease-of-use over completeness or correctness. The ideal outcome of any interaction of an end-user with documentation is a successful self-help effort. This means it is more important that end-users can easily reach their goals than that the content covers every nook and cranny of the software or is technically 100% correct from a developers standpoint. We need to understand the users' journey through the product, identify which tasks which cause most questions, and write documentation that helps the users achieve those tasks.