Yeah, there's way too many variables to ever have one set absolute-best temp to vape at. Some of the stuff I get vapes great a little below noon on my DBV. I can start off taking regular hits and then, after a few stirs, try hitting it a bit softer to try to get a few more hits out. Although they dont tastes as good, my thinking has always been "waste not". The end result ABV is usually a nice brown, one thats lost the green/tan tint and almost seems more of a reddish-brown, very tobacco-looking
But then herb i get off another source, you can hit it all day at the same temp thats perfect for the other stuff and get nothing but the flavor out of. I turn it up to about 1 oclock and it's a whole different story.
also, the ideal temp seems to also vary considerably depending on if i'm just using the whip of it i have my bong attached. I like to turn the temp a bit higher when I use the bong because i instinctively want to pull harder on it than a whip, in order to fill it up and clear it before i run out of breath. However, i've passed the bong to new users who hit it too slow and end up burning some of the bowl. So, to save myself the trouble of having to boil my glass to get the yucky smoke taste out, i like to keep the temp set to where even if someone hits it as gently as possible, it wouldnt be too hot. So there's an ideal temp for each setting too sometimes.
What i've started doing is just grind up the stuff normally and vape it kinda lightly till its a tan color and starts to get that popcorn flavor, that gives me a nice good clean buzz for during the day. Then later on i might come back to teh stuff and regrind it and push the temp slightly higher and squeeze a bit more out of it and get a more dopey drowsy sort of high. If not, cooking is always an option. So i try not to worry about whats being left behind so much.