Applying, not learning
At this level the fundamentals are assumed rather than explained. What gets trained is applying them across longer connected sections, with changing grip and real time pressure on every run.
Finding your own limit
Two days are enough to judge honestly what you can and cannot do in the terrain. On a rally or on the TET that judgement is worth more than any additional drill you could have practised.
Six to eight riders only
At this group size the trainer sees every run and can repeat a section with you alone, instead of calling an instruction across the group and hoping that it lands with the right person.
Own bike or rental enduro
Ride your own machine or take a rental enduro from BMW or KTM, crash parts and fuel included, so that a mechanical problem on your own bike does not put an end to the whole weekend.
The route towards level 4
This course is the stage before the next advanced level, and by the end of the two days it tells you fairly clearly whether that step is the next one for you or whether it can still wait.