personally, i would never grind for a bong; you usually end up pulling a lot through, and like most people said, it burns WAY faster.

as for holding the lighter to the bud, i never do it more than 1 second, literally its just a quick flick. you get more of a 'vaporizer' effect, because you arent just holding an open flame to the bud and torching the whole thing...the cherry heats up the trichomes and they sort of melt. not to mention youd be sucking up all those nice lighter fluid vapors...