Often you have to rely on intuition.
We all learn best in our own ways. Some people do better studying one subject at a time, while some do better studying three things at once. Some people do best studying in structured, linear way, while others do best jumping around, ''surrounding'' a subject rather than traversing it. Some people prefer to learn by manipulating models, and others by reading.
There are no significant bugs in our released software that any significant number of users want fixed