Indeed, when you have mixed the project well, there's almost no work left for the mastering stage. As David said.... just a little bit of gloss is all that's needed. I refer to it as "polishing the mix".

And yes, I love and use Ozone. I have a number of my custom presets that I have created for various reasons along the way. But the funny thing is, I can record two songs, basically the same genre and style, and pop in the same preset, and the preset requires almost no tweeking in one song but requires a substantial amount of tweeking or even deleting it and starting over, in the other song. Many years back, and you probably do the same thing, I began to use presets as simply a good starting point.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.