Sorry to be dogmatic about this; but knowing whether it's 5 minutes or 5 weeks that have passed (WITHOUT BEING TOLD) is nothing whatever to do with intelligence. I'm no fool, but if lights go down, then immediately rise on 2 people wearing pretty much the same costumes in a set that's barely changed how am I supposed to know (without the things I've indicated) how much time has elapsed? I agree with William Goldman that an audience's IQ is greater than the sum of its parts, but not even the smartest audience is psychic. If it's important to you how much time has passed why not let us in on the secret?
This is not an insoluble problem; why not give us an intervening scene (giving us a change of tempo, introducing fresh characters etc) before coming back to the first one?
The time we've taken away from scene one takes the curse off a line explaining how much time has passed.
This, for example, is awful: Lights down on scene one. Lights up on scene two. The same. Five weeks later.
SARAH
Annie! Have I upset you or something?
ANNIE
Upset you? Why?
SARAH
You haven't been round for weeks.
That would make me laugh for all the wrong reasons. It's too soon after the first scene. Go away from scene one, make us forget it with something fresh, and no-one will laugh when you use that crappy bit of dialogue at the top of scene three.
What gets up our noses is where a writer has clearly dusted off a rejected telly script, and made no concessions whatever to the inherent problems of live performance. It's lazy writing.
TPTB