Two internal flights. Packed a spare backpack and used it for both, checking it into the hold with the two cases.

Buenos Aires to Salta - one case was marginally over, no comment from the check in staff, but he really did seem to want me to take my backpack on as cabin luggage. Non of bags tagged as priority.

Salta to Iguassu - one of cases was 19.9kg. not a word from the wonderfully polite check-in member of staff who jumped at the chance of service someone in the sky priority lane. The 19.9kg bag was tagged as as heavy baggage and all three bags tags as priority. At the other end, all three bags were with the first 12 off the plane and rolled round the carousel just as we walked through. Perfection! Much easier in small airports I guess!