I use Ozone as a plugin in a mastering template project I have with a bunch of other plugins. Its near the last few. The others after it are for visual display of the song. (I like lots of info with lots of lights going on). These are analyzers of various types. But the string of plugins starts with BBE sonic Maximizer the rest do reverb, compression, EQ and so on. Each is used as needed with often many others turned off. The VC64 is in the string too. Ozone is the last of the sound shaping plugins and controls the overall loudness for most if not all the songs. (I really like its loudness maximizer better then any other). The other plugins are added if needed for their coloration to the final mix.
When I am in this this template it is set up as a two track stereo project that is it has two stereo tracks that I import a single stereo file into. All the plugins are on the bus. The track is set to use most of the screen with the bus using the rest. A 60 40 sort of divide. I use the other track for A/B sometimes.
I should add here I use a taste of these things in doing mastering. Not heavy duty stuff at all. The reverb for example is meant to give a sense of space for the whole mix not to add reverb to a singer or the like. Its meant to bring all the tracks into the same acoustic environment. It has to be just a hint sort to speak because you don't want it conflicting with any reverb/s that are on the tracks. In a way I think of mastering as sweetening up the mix as a whole thing. EQ is used too but mostly at the low end.
Normally I use the plugins as I have set them up that is they are ready to go with me just turning them on or off to see how things ssound or what can be done to a mix.
The mix is the hard part. It needs time and revisiting to get it right. I need to listen and think what is wrong then do something to it after which I save a new version. It mat take me weeks or even months to mix a song. Mastering usually takes a day if that. But that is only part of the process for me. Then I need to place it sonically with other songs for distribution. This will often mean I need to redo the levels for them all together so they don't jump on one another. That is done in CD Architect. Then I try it out on gear. If it is good I let it go. I am never satisfied and will revisit old songs to see if I can improve them. Also when I get hold of a new shiny plugin that I think will make a difference I will try it out on an old song. This is not a thing I recommend to others as it will slow you down in doing other things. One thing to remember is it takes work and lots of work to do this well.
Its also important to realize that great songs have been mixed and mastered with much less gear then we have.
The most important thing is mix it right first. All else is easy after that.
I got into doing it this way because if I tried to do this on the full project before I could bring my computer to its needs. Now I don't have that as a reason yet I still do it this way because it has a way of focusing the job at hand for me.