What the person you replied to described read like short read sequencing with PCR amplification to me ("each segment of DNA is read many times over"), rather than nanopore sequencing. My reply to you was written based on that (possibly false) assumption.
But if we are talking nanopore sequencing, then yes, you need multiple flowcells. Which is not a problem if you are not a private person attempting to sequence your own genome on the cheap
There wasn’t enough information to tell (on my 1 minute scan) which nanopore kit was used, but the presence of PCR does not imply short reads.
You can do nanopore PCR/cDNA workflows right up to the largest known mRNAs (13kb).
Edit:
I’m not sure if you’re saying that you can’t do a 5/20/30X genome on nanopore - that’s also not true. It only makes sense in particular research settings, of course.
But if we are talking nanopore sequencing, then yes, you need multiple flowcells. Which is not a problem if you are not a private person attempting to sequence your own genome on the cheap