T o d d P a t t i s t wrote:
However, the original question was
about whether the Coriolis effect would "benefit east to
west plane travel timewise and hurt west to east"

Actually, that wasn't the original question, which is what I was
alluding to when I said "Xerj was confused." Xerj's friend simply asked
how come flying against the earth's spin isn't faster than flying with
the earth's spin? This is straight up an inertia question.
Unfortunately, the question proceeded a discussion on Coriolis effect,
making it sound like it was related to Coriolis effect.