TL;DR
The Spoilage-related Tips and Tricks need more information in them to explain the edge cases of spoilage.What?
We need information such as: what happens to items that spoil while inside machines-- do they output to inserters even if the item was in the input slot?Can items rot while being carried by inserters? (yes, they can, and that's a big problem when outputting onto belts)
How can inserters be told to get rid of items that are about to rot? (they can't, but you can tell inserters to prefer fresher items from chests, or the opposite)