When you smoke with people these days, they only take a couple of hits. In the 90s when we smoked it was joint after joint after joint.

It's basically the cigarette filter thing; people know where they want to get, and they'll keep going until they get there, no matter how weak you make it. Which is what made filtered cigarettes worse for your lungs than unfiltered ones.

The calculus would be different if you were talking about edibles, because they actually sneak up on and can surprise you.