It is not possible to know what you need to learn.
Eliminating what is not wanted or needed is profitable in itself.
A rule to live by: I won't use anything I can't explain in five minutes.
Most things don't work like they are supposed to work.
The customer deserves to receive exactly what we have promised to produce - a clean room, a hot cup of coffee, a nonporous casing, a trip to the moon on goassamer wings.
You are going to be measured anyway by some means, fair or foul. Usually the one doing the measuring has nothing specific in mind; so he does it by the seat of his pants. Careers are destroyed in this manner.