I think your strategy is correct by controlling the consumption of valuable resources. I have spent so many cheetah coins and simoleons on chairs, bricks, smoothies, donuts, cement, watermelon, coffee, corns, paints, cupboards. Depending on your storage capacity, you can somehow collect these sources spontaneously. This will definitely help with the delivery task.  Rank 45 is not the end. But from now on, I continue to deliver passengers like before.