I think it depends on each person and circumstance (and also will depend on who the IO is too - we got a nice one). They gave me 9 months as a visitor (have a visitor record) when I crossed the border from the USA to Canada in October. Of course, that doesn't guarantee re-entry, so if I crossed again, they might give me less on returning. It was nice though, as I don't have to pay for the extension, if hopefully, I get the visa within that time period (the IO didn't seem to think I'd get it within 6 months, particularly since we didn't file the application yet when we crossed). I think the main thing to show is that you can support yourself while being in Canada while not working there (having money in the bank or showing that your spouse/partner can take care of you). I don't know that for sure, but that's my guess. I think the extensions cost $125.