If the bowl is vaped evenly (generally meaning that there's no green herb left), it means that the bowl is being extracted efficiently - that you are extracting all the goodies.
I, personally, like to only extract to the color of a light or medium coffee grind color because I value taste over complete extraction. Others like a dark brown roasted coffee color. Others take it all the way to black char.
Grind used can, in some cases, be dependent on the vape, but mostly it's personal preference. The finer the grinder the more vapor & faster extraction.
How loose or tight you pack determines your draw restriction, vapor production & evenness of extraction. Generally, the finer the grind, the tighter the pack.
Temp is also a personal preference. I don't like hot, harsh vapor so I vape at lower temps & generally use a coarse, lightly tamped grind.
All of these variables are personal preferences learned through experimenting. Get on your vape's thread & see what most others prefer, try that & then adjust from there. Do a search for grind & temp & temperature.
