Ex training + assessment/certification vs only assessment/certification

Which is the best combination in terms of final hazardous area Ex personnel competency?
1) Ex training + assessment/certification, where both come from same entity
2) Ex training + assessment/certification, where both come from different entities
3) Ex assessment/certification, where you may apply directly
IEC 17024:2012 says 3rd party assessment/certification shall happen (to be politically correct it can be realized that within one entity 2 different departments handle Ex training and assessment/certification).
So you have 3 choices, a 4th one does not exist.
Longterm I agree with those who say assessment / certification comes with training but from 2 different entities.

Keep up good work!