Can you gain deeper understanding without first gaining superficial understanding, though? And if not and our current method of imparting superficial knowledge

Can you gain deeper understanding without first gaining superficial understanding, though? And if not and our current method of imparting superficial knowledge breaks down, wouldn't there be a pipeline problem because much fewer students would get to the point where you can start teaching them deep understanding? (Imagine a scenario in which no assessment is possible in any mathematics course below the level of differential geometry. Would "we just have to switch to teaching students advanced math instead" be a solution?) Something along the lines of this is already a problem at US universities, as students chegg, stackexchange and collaborate their way through up-to-junior courses and then are so underprepared in senior-level ones that really 80% of a given class ought to be failed if this were politically feasible. At least though the current situation is more due to a lack of will than a lack of way to stop the cheating, so students are under some pressure to not make it too egriegious.