That's a bit overly cautious for identified edibles outside of a couple that can cause extreme reactions (raw shiitake, for example), but it's much better to be overly cautious with mushrooms than to be overly bold.

Eh, its not a bad test. Chicken of the woods is edible and quite delicious. But, some people(including me) will have severe gastrointestinal distress after eating. Mushrooms produce a plethora of compounds that people may react to. Much better to try in small doses the first time.

That test almost certainly wouldn't trigger your CotW GI issues -- I also have issues with CotW unless it is cooked to death, but 1/4t wouldn't do anything, so with that test you'd still be surprised by the GI issues the first time you ate a bunch.

Indeed; though I restrict doing this to mushrooms I'm familiar with. Neurotoxins abound, and that test won't reveal them.