Quantity selector for things like feeding pigs is great.
Defaults to half of the number you have, which is arbitrary. I think it should default to the last value you used. (can start at 10 or half or whatever).
I really like the 2-3-4-5 selector, but it rarely comes up, and i can't tell the difference of why it does or doesn't. I think starting at half is perfect for the [+] and [-] system.
The half makes sense, because I think most of us use that. Say you want to make cheese. You have 26 butterfly milk. Standard is shake half (13), then compress half of that (6 or 7). I tend to follow The Rule of Half when cooking and donating, mostly. The only time this is a problem, is when feeding animals. I tend to give the pigs only 1 - 3 whatevers.