I have a moderate position. It might be true that most of the thc is absorbed in a couple of seconds (but where the figures come from, I don't know. What scientist is going to do a study on that? I've never seen an article, but that doesn't mean it doesn't exist). But it seems to me that there are other active cannabinoids (cbn, cbd,etc.) that linger in the smoke after the immediate puff.

Why else would hotboxing (clambaking) your car have any efficacy? Or re-inhaling your first hit by means of a balloon? I only do that in times of famine just because it's added stress on the lungs and your body builds up tolerance to it. Maybe it all varies from person to person

I will say it is important to always blow out some visible exhaust. Absorbing all the smoke isn't worth doing; you'll only create more work for your lungs and have phlegm