It depends on you and how you want to use it. I try to explain better: once I created the shadow nand, I factory reset my sysnand to unlink and separate from the"emunand". All the games and save stayed untouched and I continued to use them in emu, because from now on I will use only this. My sys stays clean to 4.1 ofmw meanwhile the shadow at 6.00, so for now I use only one sd card. If you choose to use both sys and shadow, you'll need two SD cards, otherwise all files will be wiped away and messed up cause they share the same "Nintendo" folder. I hope I got myself explained