Vietnam to Shanghai, I left a lot of things behind (mostly books). I had to fit all of my things into four bags: two checked bags at 20 kilos each & two carry-ons at 7 kilos each. I carefully weighed each bag to make sure that I was under the limit, reluctantly adding more stuff to the pile of leave-behinds.
When I got to the airport to fly to Hong Kong, the Vietnam Airlines representative at the check-in counter told me that I was only allowed 20 kilos of *total* checked bag weight & only *one* carry-on. I was 15 kilos over weight! I paid the $120 excess baggage fee & boarded the plane. (They graciously allowed me to take the two carry-ons & thankfully did not weight them.) Apparently, if you fly from the US or Canada, they allow you 40 kilos, but if you're flying within Asia, the rules are different. I must have read the wrong page on their website.
Two weeks later, I flew Dragon Airlines from Hong Kong to Shanghai. This time I expected the excess baggage charge, so I found more things to leave behind & packed the lighter items in my checked luggage while stuffing my remaining books into one carry-on, hoping that it wouldn't be weighed. This time the lady at the check-in counter only charged me $35 for the extra weight & ignored my carry-on altogether.
I bet this move has helped me a lot with my 100 Thing Challenge.