When proficient, you can go to the ATO and do the required 3 sessions (one for each module) and a skill test. And since there is no hourly requirement for how long a module should take you can - if you are proficient enough - do all three modules in the same session.
On that basis why would an ATO want to go to all the bother of obtaining an approval to run 3 hour training sessions, its simply not cost effective.