5. Being idle is still work
Mixing is a very multifaceted process. During it engineer makes dozens decisions on equalization, compression, space treatment etc. Or decides that would be better to leave this particular instrument as it is. And this is also a part of online mixing and mastering services process - to make a decision that particular sound does it's mission great with no need for extra processing of the audio. After all ultimately mixing engineer's task is to achieve the music's most transparent and dense sound yet not to just apply own skill to all elements for no reason. Musical post production veterans have their reasons to remind everyone continuously that one strongly recommended to realize the purpose of applied audio processing. Think about it also from this perspective - mixing mastering engineer beyond dispute has to allocate foreground, middle plan and the rear one. Namely he has to allocate space depth of the music. He already has done sound foreground everything he meant to be there so with saturation. Leaving other sounds untouched engineer puts them deeper into the mix. By this
mean he emphasizes space feeling of the music avoiding sounds conflicts at the same time. In case of EDM music sound design of synthesized instruments already incorporates use of various filters. That means that lot of work on their sound elaboration performed even before professional EDM mixing and mastering. If producer's idea carried out wisely, redundant processing may only make things sound worse. To evaluate the situation correctly and to make the one and only right decision in this case - to leave the instrument unaffected - is also considered a part of the workflow. And everyone who starts learning EDM music mixing and mastering should bear that in mind.