A 'complete' understanding including every single tiny detail has never been possible in any complex subject ever and this isn't bad as you seem to think. Certain knowledge has more utility in your craft than other knowledge [0].
Also, and more importantly, some knowledge when held with other knowledge creates emergent understanding of other knowledge. You are able to intuit from core principles. The ability to understand is far more important than the ability to recall.
Also, and more importantly, some knowledge when held with other knowledge creates emergent understanding of other knowledge. You are able to intuit from core principles. The ability to understand is far more important than the ability to recall.
[0] http://en.wikipedia.org/wiki/Pareto_principle