No... let me explain it.
I do all the mixing and mastering or polishing as I call it inside the original project. Most modern computers have more than enough power to handle this task easily. Besides, if you find that you need to tweeze a level or some EQ.... you simply make the changes and export it again.....
When I export the song to one new wave.... most of the time it is done.
I open it with a wave editor and trim the silence or count in from it..... and convert it to MP3 for internet sites. I save the Wave in a folder and the MP3 in a folder.
To do this....I simply click to select all the tracks in the project (they turn a darker color when selected) and choose EXPORT and then I select a destination folder where I want the file to go. Click OK and it does the job. In MC4 and X1 I have the option to choose WHAT YOU HEAR as the preset for export.... but lacking that..... simply select all the tracks and you should be good. Mute the tracks you may not want included.