Check out this post from homestudiocorner.com by Joe Gider. He writes that it can be a difficult task for a music maker to master his own tracks. Since mastering takes a careful ear, it presents challenges when the creator must attempt to master his own work in an objective way. Often, our ears can deceive us after listening to music for periods of time, so taking breaks to reference the original will help to keep our ears in check.
Check it in full here:
One Mix, Two Masters?