I just smoked a big pile of DMT with my VG, not a glass one, the regular version, i had a small bed of used lavender buds, the rest was filled to the top with DMT, i don't know how much that is, but it was most likely the biggest pile i ever smoked and i did not break through, this is not weird for me, i never really broke through
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The first hit was nothing, no smoke, no feeling, only hot air, the second i got little smoke, and slightly drowsy, eventually i took 3 more hits and applied more heat aswell and i got a huge body high, my whole room was vibrating and kinda pixeled, but when i closed my eyes i didn't even had any clear visuals, just mildly and undefined textures, different then usual though.
I don't know about the VG anymore, my best results i always got with my bong, ash layer method, maybe i should stick with that.
I'm pretty much doing the same as you did, i hold the hits about 8 slow counts and then take another and hold it about as long as before, i have almost no smoke when i exhale either.