How often do google places listings change?

[stephen de vries]

With organic listings that can jump around pretty much all the time, but is Gplaces the same? I've heard that it makes moves only once a month?

Trying something out locally here, but getting good citations seems to be a huge pain. There are a ton of US / UK specific citation sites but finding high PR South African ones are hard. I can only seem to find 10 or so.