I've seen military manuals with basically the same procedure recommended. I wonder if there are some commonly known dangerous plants that would've slipped through these cracks.

Potato seeds slipped through the cracks for centuries! http://www.newyorker.com/books/page-turner/chris-mccandless-...

From the link: "Eat 1/4 cup of the same kind of plant part prepared the same way."

My father spent the last ten years of his career as an ethnobotanist (having previously been a government archaeologist) and his advice was increase the amount by doubling it with each subsequent test. Going from one piece of a leaf to 1/4 cup is a little bit too much of a leap, IMHO.

Also feeding it to animals. Might be a tad bit more inhumane and you could run into an issue with some animals that are able to eat poisonous food without issue, but sure is a lot nicer than accidentally dying yourself, I suppose.