I scrape a lot of video, therefore producing realtively large curated libraries [usually between 100-500GB], then used to experiment with programmatic video editing.
Having the data on device is paramount, although I find myself enjoying the liberties afforded by the ability to remote into another device, therefore allowing me to stretch my buck as opposed to dishing money out to apple.
I have 1TB on my current MBP, probably overkill but has come handy when wanting to work on my datasets in areas with lesser infrastructure. Add to that the 200GB of music and 140GB of software, I never found myself regretting the purchase.
Had I been somewhat more liberal with my spending, justifying the 2TB would not have been too far fetched, although I do not regret getting a 18TB hard drive instead
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PS. Just realised that the OP was inquiring in regards of those amount of memory usage on an iPad.
Being an avid user of polycam, storing the output files is quite memory intensive. My 256GB iPad feels cramped although offloading to an external SSD has resolved the issue.