It does not give you double drops, why the hell people think it does? It doubles drop CHANCE from boulders, fungi and plants. If a shimmering orb has a drop chance of x% from fungi xyz, this will make double the chance, so now it will have 2x% to drop from fungi xyz, it does not mean it will drop 2 orbs from it.
Also probability (chance) of , for example 25% to drop shimmering orb from fungi x does not mean that if you gather 100 every forth one, or forth of them will drop that orb. It means only that each plant has a chance to drop an orb. So you may gather 100 fungi, and get 10 orbs, or 20, or even 80 orbs. You can even have 10 consecutive drops, and then 50 not dropping. If you gather enough, I mean many plants, roughly quarter of them should drop an orb, but…
There is always but, there is something called negative bias, and positive bias. And with little drop chance for something, human minds tend to be negatively biased, so you’d think plants drop less, than they should. And if plants have high chance of drop, you will be positively biased and think, that they drop more often. That is unless you write down every drop from every plant, because if you do that, and have high enough sample (with probability in range on 0% to 100% I think ten thousand for each test would be significant enough) you can tell if the skill really does work or does not.