If you look up the Part 61 MOS (manual of standards), in the schedule of CASA administered CyberExams, you will not find BGT.
This means that it's up to the training organisation / endorser to ensure they've delivered the BGT syllabus content outlined in the MOS and proven that the student has retained it, usually by means of in-house exam.
I can imagine most training organisations will integrate their BGT MOS content into their aircraft endorsement process. (ground component, flight component, check component)