Also depends on the destination/intermediate baggage locations - for instance, airport handlers in the EU and US do not handle baggage that is over 32kg for health and safety reasons, thus most airlines simply have a blanket 32kg max allowance per bag (obviously if your limit is only 20kg, or 23kg because of class of service/airline policy, that will also apply). IATA members generally adhere to this 32kg per piece limit.

http://www.iata.org/whatwedo/ops-inf...check-bag.aspx