Unless it's changed while I was out of town, it's 100 turns, not 200. 100 turns pass quite, uh, quickly, especially if you're ` resting after getting smacked up by things.
Harvest isn't terribly efficient as a survival thing, no. It's better for low-level/risk trade goods (ala starapples) than food. Vinewafers seem useful, but they get ate through very, very quickly. Much better to grab the first level butcher and sell a harvest of starapple to someone or another for water.
I'd guess that the primary reason the cool down is as long as it is, is to prevent, yanno', going out and farming every single bloody watervine in a X radius of Joppa and coming out with 10k+ vinewafers and enough starapple to buy out the glowpad merchant. Unlike butcher, harvest just doesn't take much
risk to use, and so has th'cooldown attached to it. Using harvest as an occasional thing to do between battles, I've found it an excellent trade/water/supply supplement even with the cooldown -- I just use it in between fights on passing plants. Most non-cavern maps have at least a half dozen or so harvestable trees.
It
would be nice to see more done with it, though. New arrow types, impromptu medicines/poisons/etc, stuff like that. Maybe a skill further down the harvest tree that improves the efficiency of harvested items for you, or something.
Edit: It's around 30-40 wafers to get full from th'auto-eat point, iirc, not 400. Maybe up to double that, 60-80, s'been a few days since I played. Just seems like 400, 'cause each individual one gives so bloody little nutrition. Which is what you meant, o'course, but numbers~