Having just 2 proper meal services on an 18+ hour flight seems meagre to me... when in contrast if you do SIN-FRA-JFK, you'd get 2 meals for each segment.

That said, for in-between meals, if you're not happy with the sandwiches and soup noodles on offer (I generally don't find these to be interesting enough) you can always inquire if there are leftovers from the previous meal service, and crew would normally accommodate by heating up an unserved meal for you.