there's plenty of really strong dudes who smoke everyday. i've been on training rides w/ a russian speed skater who would light up a cigarette on the bike. and i know a us olympic nordic skier who told me (over a joint at our summer job)the whole team are dope fiends. sure i know , i know , we've never been hot shit at nordic skiing yadayada.
i doubt anyone on earth would say that hitting the b allows for optimum training-physically speaking. and obviously the more you hit it the further from optimum you get. still, if it works for you mentally, (the mind is very powerful) and you're getting results, i'd say that smoking and training is better than no training at all.
just don't have any accidents.