Only hold yer hits for ten seconda max. Most of the thc is absorbed in the first 3 seconds. after tne, your jsut fucking yer lungs man.
I jsut go for straight up weed, and not filter it at all with tobacco, unless you trying to make it last longer or something.
i guess if your a super lightweight, then tobacco would help, but cigs never did shit for me. ALaways got my friends a little light headed though.
Don't worry abouth ow long a bong should last, just smoke it. I find bong lasts about maybe 10 or 107 minutes, depending on how much weed is in the bowl, if I'm in a rush, I f im not in a rush, I stop and play my geetars between hits and shit.
even if you take hu8ge monster hits, maybe 15 secs MAX for a hit, just take normal sized hits for liek 5 seconds a piece, and you will get mucho lifted my friend.