I've recently started using smart lock. I've enabled two features: a trusted place and a trusted face. I cannot understand if in this case both of these mechanisms should pass to unlock the device or passing any one of them is enough. For example, is my face (theoretically) enough to unlock my device when I am not in a trusted place? I haven't been able to do so, but maybe I'm just doing something wrong.
Smart Lock will unlock your device if any of the trusted places/faces/devices/etc. are found. Configuring multiple verification methods does not mean that you have to match all of them. You should be able to unlock your device with just your face without being in your trusted place. You can also unlock it by being in your trusted place and not showing it your face.