Once all the trees are planted, there really isn't any advantage to using the lift beyond the small increase in available food. The food is added to the bin the moment the villagers pick fruit from the trees or pick up the dropped fruit from the ground (after all of the trees have been planted). In order to see the change in the food supply, you need to watch as the fruit is picked (or picked up from the ground). Also, the villagers eat a certain amount of food, even when you don't see any of them at the food bin. If food is eaten at the same time that fruit is picked, you may not see a change in the total food supply. This is normal.
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Barbara
Unicorn
Last Day of Work