In NJ (Newark to be exact), I've weighed "bags" of china white dope/H/diesel. And I say "bags" meaning the unit of measurement: 10 bags = 1 bundle, 5 bundles = 1 brick, 10 bricks = 1 sleeve // also, the idea that 100mg = 1 bag, 1gm = 1 bundle, etc. That being said, I have a triple beam as well as a digital scale that's accurate to the .000 (which I calibrate quite often with legitimate weights, as opposed to dollar bills or whatever). I'd say that over the years the bags have definitely gotten smaller (and the prices have gone down, and this could be a whole other topic itself, so I won't get into it here)--but lately, I've been seeing a bag weigh about .06g/60mg on average. If it's anything more than that, it's usually just extra cut. Honestly, some of the best stuff I've seen around lately was really light, but high quality stuff (example: people who normally do 7-bag hits would do only 3 bags of this stuff and get a better high)...and they were only weighing in at .03g/30mg...but again, you only have to do half the amount for the same high. Plus, then it's cleaner--literally no residue left behind in the "cooker"--and I put "cooker" in quotes bc in NJ you shouldn't need to cook your stuff (but always filter!).
I know some people that do weigh their bags and complain relentlessly about the fact that they're light, and I try to get the point across to them about the fact that it could weigh more, but then it'd probably just be more cut, so if the stuff is good, I wouldn't mess with it. The group that were selling the really good stuff would bag it up themselves, and while they're legit people that I am honest with, I know they aren't going to double up on the weight, and they've got the best stuff around, so I wouldn't mess with it.
Regarding the comments about being honest with dealers, I do still agree, and they would correct any issues that are out of the norm--example: if a bundle is a bag light, they'll make it up. Also, they are super legit about weighing out white girl and let us test the H, ask how each batch is, ask for recommendations, etc, but still I don't expect to get .1g/100mg bags. Sorry for the long explanation!