The only thing that gets you more high from holding it in is the lack of oxygen to your brain, just get more of a resinous build up in you lungs plus if your using a lighter your getting an affect from the butane too, all very bad..It's bad in the sense that inhaling any carcinogen is harmful, but does it get you more stoned? Absolutely, based on personal "research" over the last 2-3 decades.
Yeah i heard 5..to many bullshit studiesDon't quote me, but I've been told that it takes about 3 seconds for your lungs to absorb all the thc that they can potentially absorb from one toke. Holding your breath any longer than 3 seconds only serves to starve your brain of oxygen, most definetly promoting a light-headedness, a sometimes desired effect however not a result of taking a fatty toke.