I've been somewhat of a freak when it comes to my cigarette smoking. I seem to lack some liver enzymes or something, I already know I'm probably CYP2D6 deficient from my experiences DXM, tramadol, and Codeine but it also seems that nicotine takes a long time to find it's way outta my system too.
When I first started smoking I would feel effects for about an hour after my cigarette. I've been smoking for 3 years now but if I go strictly by cravings I would only smoke about 3 throughout the day. Slow metabolism of nicotine = less cravings I guess.
Nicotine is probably the only drug that I'm happy I handle slowly.