If you use the Android devices as alarms, you may need to check your Settings again. In Android version 5.1, Google provides “Until the Next Alarm” option, but the function disappear in Android 6.0, this has caused some users. So Google Android 6.0.1 push, will add back the missing function, now, in this sorry tale, this function seems to be gone again.
According to Reddit related discussion topic, some users see this option on the screen.
Android Central reported, this problem occurred in the Nexus 6p phones, Reddit users also mentioned the Nexus of 5.
However, the “lucky”, not all users are the latest version of Android 6.0.1.