Watching yourself in demos is a waste of time as in, you never can improve anything off of that, every pug is random because you don't play the positions that you have set to do on an actual team so the results are more random than a game of hearthstone.

If you want to get better at cs you just play the game more, that's it, you improve with time, you get to Global Elite in matchmaking and try Faceit.

If you get on a team I get it, watching demos is crucial because you can see your teammates and what mistakes you did and what you could've differently with your teammate but in pugs it's ALL random, everything in random as fuck, only your individual skill matters.