After reading it deeper I frealised it's not waht I'm thinking of.
I thought of 1 docker container that has nzbdrone, sickrage, couch potato, transmission, flexget and headphones all together. So instead of needed 6 containers, I just use 1.
They all pretty much work together to produce a desired result.
I'm assuming as single container would mean less HD requirement and less memory requirement. But maybe I don't understand the unerlying advantages of Docker and it makes no sense.