I would suggest that a "one shot" is for the duration of the current scene & location, but that's not necessarily mutually-exclusive; a scene can potentially take place in multiple locations (eg the scene starts with a girl in a bar, she gets drugged, taken out the back to an alley, naughty things happen in the alley, the assaulter leaves her in the alley...then the scene ends). In that example, if the girl then tries to follow the assaulter it's no longer a one-shot, as the scenario then has continuity into other scenes and locations.
How many posts does that take...? Totally between you and your partner.