My own rules for how much to scratch off depends on the size of the country. For most cases, if I've been to even one place in a country (for a reasonable amount of time), I will scratch off the whole country. However, this doesn't apply to the 10 largest countries in the world. In those cases, I will scratch off the largest sub-unit in a country. For instance, if I've visited the US, I will scratch off the state I was in, rather than the whole US.
But for Russia, there isn't really a clear delineation of areas. There are so many different kinds of sub-units: federal subjects, administrative divisions, municipal divisions, federal districts, economic regions, and military districts. So, my question is: where would you draw the line within Russia? Or do you simply scratch off the whole of Russia?