The urge or more accurately the thought or faint memory does come sporadically, years and for some people, decades after their quit. But they are really sporadic for most, sometimes occurring less than once or twice a year after decades.
It is comparable to when a certain trigger reminds you about a relationship you were in decades ago. You may have a momentary feeling of longing or sadness or relief, depending on the situation, but it is not like that resurgent memory effects the rest of that day or the rest of your life. It passes into oblivion again, until the next time some thing triggers it again.
That is what the thoughts for cigarettes are now, a reaction to a trigger that shall pass, not a big deal. If a puff is taken in reaction to a trigger, then you have a full-blown relapse and the course is dramatically altered. Now every 20 minutes or so your body is going to demand nicotine and cause a basic debilitation or at least a distraction for any other activity you have to do in that time period.
This state will go on for the rest of your life until the smoking either cripples or until you have to quit again and go through a long and sometimes tenuous quitting process that may take days or weeks to feel normal again. Either scenario is raunchy when really analyzed, although one is far worse than the other.
The best situation then is don't end up in either state, smoking again or quitting again. The only way to avoid either is to never take another puff!