Not sure we can hang that one on experience.The "don't leave anything out" style of teaching
Generally, more experienced people know
what's important, and what isn't. My father
once said to me over 40 years ago, "I'll teach
you to fly. Someone else can teach you the
chickenshit".
I think the "don't leave it out" comes from
fear of Transport, and a lack of confidence
and knowledge of the subject matter.
I agree that what you choose to leave out
(and not distract the student with) is crucial.