If you're, for example, using spaced repetition to learn a complicated foreign script, which can be written in numerous ways (numerous printed fonts, and handwr

If you're, for example, using spaced repetition to learn a complicated foreign script, which can be written in numerous ways (numerous printed fonts, and handwriting styles), you have to be able to recognize and name these variants. That is well and good. If we are training name to location for a set of countries, the front of the card is the name. You only need multiple versions of that if the country name has spelling or naming variations. If you're going from map shape to naming the country, and you want to be able to do that in any orientation, then you benefit from training on map rotations. I'm guessing four rotations ought to be enough: upside-down and ninety degrees CW and CCW. That already quadruples the training set; there has to be some reasonable balance.