Answer:
OK so almost no one ever actually asks me this question, it's just one I wish more engineers would ask.
First, DO NOT name all of your mixes MixFinal_01. When the mixes of all of the songs are combined into the "master session" It will not be possible to tell the songs apart. It may seem obvious to you if you have listened to these songs for weeks or years, but to the mastering engineer it can become VERY confusing. Also consider if the name will be obvious to me as an instrumental or in a foreign language (foreign to me). Also the names of tracks often change during the production. Just keep the naming consistent and produce a song titles list for the mastering session. On this list show the original working title of the track and the final title for the CD and the chosen mix name. So often the mix name has to be an abbreviation of the title and it's very handy to know the exact filename so that a name search can be performed when a file mysteriously goes where it should not have. Pesky soundfiles.
