Focused build offers rich features to capture requirements in terms of flexibility and integration.
Requirement captures key information such Value, priority and effort estimate and it is also flexible such that you can create requirements with minimum information and develop it later. Focused build gives the opportunity to capture requirements quickly especially in process discussions and workshops and they can be further developed in collaboration with business. Requirements gathering is a collaboration effort between business and IT.
Remember, clear and unambiguous requirements are key to the success of an SAP implementation.