When do you use spot metering on 1dx or 5d mkIII?

I am curious to learn for what situation people use spot metering. In particular, since i do mostly portrait, do any of you use it for portrait when shooting without a flash? I usually do not play with metering myself but by mistake i took a few portraits with spot metering inside without flash with my 1dx and actually found the skin tone better this way. By better i simply mean sometimes with the default metering (evaluative i guess) in low light it can create too much contrast and shadow on the face which then becomes harder to recover i found. I know it depends a lot on the lighting for each shot, but this small test made me realize there is a world to discover out there regarding metering which i still know very little about...:)

Just not sure if i risk overexposing too much other part of the picture if i use this consistently... Thank you for your insights...

When you have a subject backlit, you can use spot metering on the face telling the camera to forget about the bright background. Yes, you'll have a better shot with overexposed skies, but it beats having an underexposed face and bringing in noise while trying to brighten up the face.