Quite often, we have more than one Delta and over, and except for Nice, Lima, South Observatory and Dubai, every destination covered needs Flight Catering. However, the Catering building supplies only one unit every 12 hours, so if we need more, we either speed it up (1 green) or upgrade production for one more slot (10 units). But many of us save up greens for land, more powerful power sources or Spy Glass/Dice/Golden Dice- what can be done then? Right now, some of us trade flight catering just to have enough numbers. Is upgrading/speeding up worth the greens?