You shouldn't be sweating over that kind of thing, so long as you have all your hardware connected to power (so that they work) it doesn't really make a difference. The optical drives don't use up too much power because they are not running all the time like your hdds are, so you don't have to worry about overloading one particular rail. I personally use as few "strips" as possible to have the inside of my case tidy and the airflow clear.