You have actual professional experience, so I guess I'll have to defer to you, but that's not the definition I know. I'm not saying you're wrong, but if the master isn't the shot that gets EVERYTHING in the scene, then what defines a master?
Perhaps I should have been more specific - jetlag from a 12 hour flight is thrilling haha.
What I meant was the master doesn't have to be an ultra-wide 18mm from 20' and capture everything. If your scene is two people talking, then your master
could be a 35mm two-shot. It just depends on how you design your scenes. If you need an ultra wide shot, then that's going to be your master, but if most of the scene plays out in MCUs, CUs and even some ECUs, then your master doesn't have to be a super-wide get the table in and their legs and the background and deep focus blah blah etc. (as I've seen some Directors want). Your master could be what I like to refer to as the Mid-Wide - closer than a wide but wider than a mid. As long as it covers their actions.
But, it all depends on what you, as the Director, want. I prefer to work with interesting coverage that furthers the story, rather than simple standard coverage - I'd rather have a slow dolly in that cuts to an ECU than a wide, mid, cu, ecu etc.
As an example, if we were shooting a couple chatting and laughing sitting on a hill overlooking the city in the middle of the night cliche love scene, Even though the Director wants to end the scene on a really wide shot of the whole city with their backs to the camera, If that was the only time we'd use that shot, then I wouldn't treat it as the 'master', instead I'd treat the mid-two shot that covers all of their actions for the entire scene as the master. The mid-two (in general) is going to be 10x more useful for the editor to cut back to than the super-duper wide where all we can see of them are silhouettes.
This is all generally speaking, it's going to differ on a per-project and a per-scene basis. But I have seen Directors get caught up in making sure we get full takes that are perfect of the 'master' wide, when he knows we're probably only going to use 15 seconds of the 4 minutes we shot.