It is a matter of right technique and proper dosing.
You have not motioned any of that. How do you measure your dose ? What is your smoking technique ?
Speaking from my experience I make sure nothing is left in my GVG before another use.It is normal that there is some residue left after use.
I always wight my dose on .001mg scale. Make sure you don't burn your spice as it will be too harsh to smoke even with GVG. I only use cooper mesh no screen necessary. I melt spice into the cooper mesh before vaporizing.
We are each of us angels with only one wing, and we can only fly by embracing one another.
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We are all living in our own feces.