Studying past games of masters is (almost) never a waste of time, especially well annotated ones. You're not going to learn something from every single game but you may remember games you'll want to look at later on esp. if they have openings, middlegames or endings that you're interested in.
If nothing else I find playing thru the games of Fischer, Capablanca, Rubinstein and lots of other great GMs highly entertaining - just like admiring great works of art or listening to the works of Beethoven, Mozart, Bach and other great composers.
For now books like "The 1000 Best Short Games of Chess" and "500 Master Games of Chess" by Tartakower and Dumont would be helpful IMHO, and/or "The Most Instructive Games of Chess Ever Played" or "Logical Chess Move by Move" both by Irving Chernev.
Look for used copies at amazon and eBay.
I would like to weigh how important it is to study past games among opinions of this forum.
There are many methods to improve Chess ability: playing the game frequently, practicing tactics, hiring a coach, reading books or articles or watching videos...
but where would studying games of others rank among the ways to improve one's chess?
I'm reminded from the 60 minutes story on Magnus that he has memorized some 10,000 games. I don't view that as remotely possible to a simple serf like me...but is that what helped stoke his genius? Sheer knowledge?