For me, the most important thing about mp3 files is to look at it as the final consumer file format. It is not a format that you should work with during a production. But when the production i finished, it is a very fine file format for playing to the end user.
During a production i always work with the highest possible quality at hand (often 24 bits, 48 kHz) and in a linear (pcm) fileformat like .wav
When the production is finished i convert to mp3 320 kbps when delivering to the client. Nobody can tell the difference and it performs way better in terms of speed for streaming on the web and stuff like that.
Mostly i work with
mixing and producing brandingfilm and other kinds of
videoproduction in a productioncompany called Nerd Productions in Copenhagen - but the theory is also applicable when mixing music