I don’t use any apps myself. But I do encourage my clients who are into using apps to find one that they like and use it. Those that do use apps for tracking seem to all use different ones. We do review the input together on their smart phones once a week. I make notes from the app in their files. And my showing interest in checking their tracking reinforces their tracking effort. I don’t discourage anything unless it seems to be distracting them from their goals.