Electronic voting methods are easier to change. Having a hard copy at least guarantees the ability to physically recount.
If anyone wants an example of what appeared to be an orderly and well-run hand count, just go back and watch some of the videos about how Brexit vote was counted.
If it takes more than one day to count and verify counts, so be it.
Yeah, paper ballots are good, until you lose a box of them and overturn an election.