A parsec is a measure of distance
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The why would he say that he made a run in 12 parsec, if it is always 12 parsecs.
It is a definition of a time unit.
as a light year is a distance measure not a time unit as in how far light will travel in one year.
Because he plotted a course through some asteroid section that was dangerous and he was able to go directly through it, instead of around it—thus doing in less time AND covering less distance.
Of course…none of it is real.