Original sentence: But in turn, the organization publishing the HIG might withhold endorsement of the application.Developers sometimes intentionally choose to break them if they think that the guidelines do not fit their application, or usability testing reveals an advantage in doing so.HIGs are recommendations and advice are meant to help developers create better applications
Edited sentence: But such departures should only be taken when there is evidence from usability testing that the interface is improved.HIGs should be taken at face value; their recommendations and advice are meant to help developers create better applications, but developers are naturally free to break them if they think that the guidelines do not fit their application.The only repercussion for doing so may be that the organisation publishing the HIG does not give the application its blessing