Sporadically in example sentence
The premise is stock standard enough that a brainless monkey should be able to make a movie around it, but the script is so unbelievable, and oddly structured (moments of grainy flashback flicker sporadically through the plot, gradually advancing an all too obvious and predictable back story), with characters introduced in tossed-off, sitcom-ish scenes, never to reappear again, that its hard to get through more than a scene or two without groaning.