They have 20 auditing stations.
If they man all the stations, 24 hours a day, 7 days a week, each station needs to audit one ballot every 30 seconds or so.
They're not moving nearly that fast. (And they're not always using all the stations.)
Will they speed up as they get better at it?
Good point. I know the audit will detail what they did at the end, but for transparency, why not explain what they are doing?
What I'd really like to see is someone open up one of those boxes and go 'holy crap, look at all these bullshit ballots!' Then the audit need go no further. Suicide weekend commences.