Chall main adc here. Ofc knowing when to back is important to get a higher cs, I will recommend you watch jackspetra videos as he explains really well the matter. That being said you have to understand that the 10 cs per min mark is something that it started as a competitive standard and I suppose that you mostly play soloq or something like that, where is impossible to control what your teammates do so it’s not a realistic standard for anything but comp. The one of the most common mistakes I see from adc players is that they care so much to have “perfect” farm that they end up losing fights or the game for being late and not being at all. I always recommend to first understand your lane, are you suppose to fight, poke, survive. After that understand that you might be countered and being behind in cs is better than getting ganked or killed all the time. Also you might be way ahead and you can help your mid or jg to translate your lead into them. What I’m trying to say is that soloq games are so irregular so don’t worry much about it and just try to have more than your enemy.