at least this is my experience from DL TPAC:
a lot of time when I press the FA call button, no one came ....
when I walked to the service area, most of time I saw US FAs just sitting there and chatting ...... (what a surprise ....)
when I flew the Japanese based airlines, this never happened to me
I found what's even nicer about the Japanese airlines is even you fall asleep when they deliver meal(s), they'll left a sticky note in-front of you which gives you a chance to get the meal later
what I saw on the DL is they just pass you without leaving a note and I'm not sure whether you get the meal later on .....

also food is just way better on japanese airlines