I agree. Relying on an app and voice guide is a bad idea. You are supposed to not concentrate on anything, except for breathing, and having a voice guide would take away from that.
Joining a community of practitioner is also very beneficial - this is how in the Buddhist traditions meditation is taught and discussed - however it's not always possible depending where you are.
Meditation though is not a silver bullet. If it works for you great, if it doesn't benefit you, move on.