Today's "deep thought", in chess as in many other things, it's important to pause to understand. A pause can even be the difference of life and death as in the old example "Execute, not pardoned." vs "Execute not, pardoned.".
In chess, especially nowadays, it's easy to end up in front of the computer clicking thru games at a rushed tempo in preparation for a game later in the evening or next day. And then, at the board you find that most of what you saw has just went thru your skull without leaving much trace. So, seeing, reading, listening without reflection is just a waste of time.
While on the other hand, going thru just one good game at a leisurely pace may be enough to actually feel prepared! It's easy to forget that every move in a game has been the product of at least a few minutes thought, at times much more, and thus each move needs to be consumed in a similar pace to make an impact.
The same also applies when playing chess. Especially in blitz it's more important to find a rhythm of play, than gaining time on the clock by quick theory moves as this can lead to a rushed rhythm and oversights.
The following game from the recent Blitz World Championship is an excellent example. I'm especially impressed by the coolness of Aronian towards the end of the game, as he's able to keep his rhythm despite only seconds on the clock - really making use of that 2 second bonus per move! In a winning position with little time left it's very easy to focus on the clock instead of the board, and that's when howlers appear!
And to round off, here's an old great song by Leonard Cohen which is also a good example of the value of pauses. Just try to read the text of the song as if it was a normal text and the magic goes away immediately!