Be careful if you put a camera into SPOT metering mode and start shooting in Av or Tv mode...it can lead to wild exposure fluctuations, and if you're not paying attention to the rear LCD, and are just blazing away, it's possible to get huge deviations in the exposures from scene to scene, or even shot to shot, just based on whatever comes to rest in the center of the viewfinder, where most spot meters meter ambient light--smack dab in the center of the finder.
I really see little use for spot metering in 2017 on d-slrs; you've got a histogram and blinkies and INSTANT, on-the-scene "developing" nowadays...it's easy to take a conventional center-weighted reading, or a matrix meter reading, shoot a shot, then review it, and see how well the exposure turned out.
Spot metering is fine for experienced shooters, but again, it's got some very serious consequences if it is used in a slapdash or forgetful way! Believe me--I've screwed up in spot metering mode, in the way I am cautioning against, and it can be UGLY!
Spot metering is really for "experts" and "serious" shooters who are paying very close attention,all the time. If you think you're in CW or Matrix in AV or TV modes, but are actually in spot metering, oh man, it can be horrible to see wild exposure swings of 3,4,5,6 stops!