the chunkier it is, the less likely they mixed in random riffraff in. if you are freeze thawing, hot water bathing and/or pressure cooking, the chunkiness ceases to matter. pretty much you want/need fine af for STB teks that process a large volume with minimal effort, geared towards decent enough purity. STB and dry teks have poor penetrating power. DMT exists in anatural polymerized/polymorphic state that is speculated to sometimes be very unreactive or insoluble, while bound to a solid substrate. i.e acid has a hard time soaking through and converting DMT since it kind of needs to be overwhelmed by a lot and/or very strong acid to let go quickly.
Do a few freeze thaw cycles, then pull, and then freeze-thaw again while you process that first pull, even the chonkiest of barks are no match for ice based cell lypholization