Like Chuck, I turn off VoiceOver when the app is not accessible such as an introductory tutorial is an image and I need to go to the last page to continue to the app or etc. I also turn off voiceover if there is a graphic item that needs to be tapped on, which is by trial and error if it will work. In the MBraille app, I turn off VoiceOver because there is a self-voicing feature that is more responsive in using the app.