Having just only one scrolling background, which means you are having just one big scene, you will have to work rather disciplined from the very beginning, because you gonna have to store all your objects, characters and animations in this one scenery.
It helps me a lot, that the common game is divided into different scenes and the usable obejcts have to be defined therein and not on one single stage.
I once had the idea to make an adventure, taking place in a hotel, with all rooms visible and vertical scrolling. And I totally messed up the walking areas and objects, because it early became too complex for my tiny brain.
I don't say that it is hardly possible, but for me, with every single object manipulable inside those several rooms, I was just not prepared.