ecj, there's no real definitive answer. I don't have the books to hand but they say something like wind with landing clearance and more if the pilot requests them (instantaneous or otherwise). Many controllers use common sense and pass more reports if the wind is all over the place.
If they're a nuisance all you have to say is "no further windchecks" or something along those lines. Not that I've ever seen it of course
, but I have heard that some pilots ask for windchecks down final until they hear one that's inside limits and then say "no more thanks"