Doing overnight flights or leaving your device unsupervised is never easy. Some unfortunate pilots, if they have not set up their plane correctly, can unfortunately loose control over the aircraft once they’re no longer at their device.
Don’t leave your device right after passing 10,000 feet. At higher altitudes, there is a lower density of wind, which means that the aircraft’s engines need more power. And if this kind of power isn’t supported by the respective engines, you could stall out before even realizing it.
This is why I’d recommend you supervise your device until reaching your cruising altitude. When you think that everything is perfect and no risks could potentially happen. You can leave your device unattended.