Jane had her party, so we're slowly working our way through thank you notes. It's so important to me to express gratitude in a written form, even if Jane said thanks when she opened the gift at the party. (And some of the children had left by the time she started opening.) Jane's 7 so can write and is writing the notes. She's also drawing pictures and making it take entirely too long! But they will get done.
The parties we've gone to recently - both for Liv and Jane - haven't come with thank you notes afterward. Some of that is definitely logistics - without an address or a reliable way to give notes what's the point? And another, probably bigger, part is culture - it's not that important here to give written thanks for something small like a $10 birthday gift.
I'm OK with that, but as for me and my girls we'll keep writing our notes!
Edit to add: We got a thank you note for the pumpkin party! The mom didn't know who gave which presents but she did send thank you notes!