Earlier quoted context omitted.
On this topic, what resource do you think is a really good one for learning mastering?
Try messing around with buss processing and track sequencing while referencing other recordings in the same genre. Just make sure to keep the unprocessed tracks around, and err on the side of "less is more". There's a lot of overlap between the aesthetic skills needed for mixing and those needed for mastering. The profession of mastering is much more than that, but generally when people ask this question they want to…
For me personally, I'm a bit past the messing around stage and wondering about specific areas of exploration.
I'm just always thinking mastering engineers know some techniques I've never considered, especially in terms of creating that upper register 'shimmer' ... is there crazy stuff happening using m-s and then diving in to certain frequency ranges?
It could be that it's more mystique than real?