Well, backing out SHOULD end it, but there is a chance (and since I do not know the makeup of the OS or its applications, I have to kind of go on hearsay) that applications can leave small processes running in the background upon exit.
For example, there is a threads in one of these forums about a battery drain related to Bluetooth and Xbox Music. Someone suggested that it might be independent of Bluetooth and be 100% on Xbox Music. Why? When you close out Xbox Music after starting a song, hit the volume rocker. It still shows the last-played song, and if you hit "Play," it will resume where you left it, no? There might be a small process in the background keeping that going, and if you have that going on with multiple apps, it can be a substantial battery drain.
Oh, tip:
With Portico, when you reset a phone, the brightness automatically goes to high. I have mine set to low, but I have to set it to something else, then back to low to get the brightness back to low.