Very anecdotal and somewhat niche use case, but as a performing musician and educator, the iPad 12.9 is the best way to digitize and carry around not just music/charts/setlists, etc, but also all teaching materials/books. I know that for many, many musicians, the iPad 12.9 is the best option for screen resolution & size, ease of use for notes/markings when paired with the 2nd gen pencil and an app like ForScore, storage for their "sheet" music needs, and the quad speakers are also a huge help when trying to play a metronome or other accompanying sounds with my students or even in rehearsals with small ensembles. A lot of this work doesn't require the chainsaw processing power of the newer iPads - I'm still using my 12.9 Pro from Sept 2020 and have not felt any need whatsoever for the M chips, but, again, niche use case here.