As with most arts, the craft of music and audio has a great deal to do with editing. Once you have a collection of raw materials, the process of shaping the final work is largely a matter of deciding what to leave in, what to take out, and how to handle what you've kept. That process amounts to no less than a series of decisions rating the importance of each element under consideration, and nothing could be further from absolute: value judgments depend entirely on context, and most especially on your objectives and your frame of reference.
The most oft-discussed aspect of the editing process concerns density. Many believe the greatest impact comes from restraint; one famous saying has it that “perfection is reached not when there is nothing more to add but when there is nothing more to take away.” That's a restatement of the old maxim “less is more” — more or less.
In my view, that is frequently but not always the case: sometimes more is more. Jimi Hendrix felt that the effects and filigree he added in his final rounds of overdubs were the most important aspect of his recordings. Carl Orff's Carmina Burana just wouldn't be as rockin' with a chamber ensemble and a vocal quartet as it is with a double orchestra and a 200-member chorus.
This is part of the larger question of the level of detail (or LOD) at which the artist can or should work. The more broadly one considers this question, the more vital and multidimensional the discussion becomes. It is not enough to ask whether more or less detail is needed; it is also necessary to balance levels of detail between different elements and to define what constitutes fine detail.
What does the expression “good enough for rock 'n' roll” really mean? Not that the element under consideration is insignificant, but that, taken alone, its importance to the work as a whole is limited. For instance, some of the greatest rock and jazz music of all time does not adhere strictly to tempo. Carl Palmer often rushed fills in classic ELP recordings; what mattered, however, was not that he hurried noticeably but that the rest of the band stayed locked with him — or that everything was so raging that the tempo variation was okay. Something of greater general importance overshadowed the tempo variation.
An example from the other side of the coin is dealing with noise and leakage on tracks. In the heyday of analog tape, each track contributed a little noise to the mix. The noise of one track was often not objectionable, but 16 or 24 tracks combined sounded like a snake pit. Thus, muting tracks that weren't playing was one of the first essential moves mixing engineers made. An equivalent practice today is to put fades on both ends of every region in a DAW document in order to avoid tiny clicks and unintentionally abrupt attacks.
One of the most fascinating LOD topics is subliminal effects. I'm not talking about one-frame messages urging listeners to buy Flondopowicz Beer, but about the impact of sounds on the edge of perception. The barely perceptible can be incredibly important.
Returning to tempo: what makes it so impossible to sit still while listening to a great blues shuffle? It is the amazingly fine level of detail at which the rhythm section works, both individually and collectively. It is the precise fashion in which they do deviate from that click that makes blues so compelling.
Audio post-production is another area where subliminal detail is important. If you see someone using an expensive 1920s-era silver cigarette lighter in a movie, but the Foley artist used a Bic Flic, something feels wrong for a moment, disturbing the immersive experience of the film.
Editing sometimes makes me think of sculpting, where each tiny chip must be made with the finished product in mind. So, as you place your chisel each time, consider whether you really have the LOD-down on that chip's impact before you swing your hammer.