For me, a mix is not a rough mix until I am done tracking. Regardless of the overall quality and cohesiveness associated with a project, I am not bouncing tracks to stereo and seriously evaluating tracks as they pertain to a song until they are all somewhere in the project, whether they be sub-mixed, muted, or frozen. I may have not even decided whether or not I will even use a track until I have completely finished transferring my musical ideas from my mind to my hard drive.
Often, I will choose to use or not use a track only after I have the opportunity to listen to it along with one or more other tracks, like say a Bass track in a group of other Rhythm instruments.
I prefer to do that by soloing and creating sub grouping in the console section of my DAW or mixing console. I may want to change the part musically or audibly, so mixing down or bouncing tracks at this point is pointless.
Rough mixes, for me, are used for perhaps honing overall FX and setting the final send, pan, and volume levels on my busses, and usually entails several different formats associated with several different ways we listen to music. It is where I tweak the Compressors and I am checking for clipping and saturation levels of different tracks as they modulate amongst the other tracks in a mix.
Of course, my personal workflow dictates I am doing this throughout the entire process of recording but the process is progressive, in that earlier tweaks may have been before other tracks and FX were added and though necessary in the overall creative process, are not permanent, as in a final mix or a contending rough mix.
Rough mixes is where I really focus on bringing the mix together as a complete entity. I think less about tracks and more about the completeness of the song.
It is less about,“How do these tracks sound together in a mix.” It is more about, “How do these tracks sound in a mix, at these levels, in these formats, on these speakers, on my personal audio system or in my car or on a surround system (That is a whole different story).
Rough mixes are Keepers, whereas up until that point, aside from the musical and technical data (Mainly MIDI and Automation data), everything else would be considered Scratch Tracks.