I concur with the above. Although I must admit that by day three (or two - even the end of one sometimes) tolerance and cravings have risen to the extent that it's hard not to just wap out a spadeful and hoof it down. It definitely gives a cleaner hit when chased in small amounts with ultralow flame - little and often. For big whacks I tend to go for the bed of ash onna bong with more ash on top method. Definitely very wasteful but fills the need for more, more, fukkin moooooooore that's firmly entrenched a coupla days in.
Also, the back thing is horrid. Can get extremely uncomfortable. I'm almost certain it's caused by sitting in the same position for waaaaaaaay longer than you notice rather than any direct effect of the drug itself though. Trying to remember to get up, move around a bit and stretch regularly ain't easy but definitely worth it.