user806: If you have been to an online chess server, you will notice that almost all titled players always play quick games (3 0) at a max.
On the other hand, if you go to tournaments, it needs cool thinking and not instantaneous moves. 
I am surprised, then how do they maintain this balance? Doesn't playing too many quick games spoil their overall playing ability?

user881: Playing speed chess makes you concentrate more during a match.

user870: Very simple, playing and winning in the faster games such as Blitz  will give them confidence when they play games that lasts days together.

user862: Blitz allows you to collect game experience fast. Blitz could improve you in:

Quickly test some new moves and get adequate response in a real game.
Learn moves so that you will waste less time for thinking in a real game.


user1420: I am an active member on online chess server http://www.chessfriends.com. I played there more than 5800 games. My stats as white are exactly same as black. I prefer playing 1 minute games,  but sometimes I play 3 minute or 5 minute games. My experience is, that playing bullet or blitz games improve my tactics skills a lot. I have 2300 Fide rating, and I am still able to play 6 hours National league games, without any problems.

user342: Who has the time for a nice 30 minute game anymore?
Being a titled player does not mean that all of your income comes from chess and that you live a life of luxury (If only! :P). Most titled players have jobs, families, or other endeavors to deal with on a daily basis. As such, it is nice to sneak in a few quick games when there is time to play. This is why it is popular, because it is easy to use no more than 6 minutes to play a quick 3 0 game and then be on your way.
Why play one when you can play many?
More than that though is the appeal to play a larger amount of games and positions. Playing one game which takes many hours has its place and is great for your chess (I think slow chess makes my Blitz better), but it is still only one opening that was played. In an hour, it is possible to play up to 10 openings by playing 10 3 0 games. Or, if you are feeling in the mood for a good sprint, 30 1 0 games.
Experience
It is also nice to build those natural reactions. When you play those 10 games in an hour, or perhaps in a week 100 games, then you begin to see positions that can be transposed into, or certain weaknesses in the opponent's position out of experience rather than a keen observation.

user757: When defending his title at the World Chess Championship 2012, Anand defeated Gelfand in the rapid round. He was able to put time pressure on Gelfand in all four games. In the second game with white, Anand played his moves so fast that Gelfand was forced to make moves with very few seconds to spare.
Being able to perform well in rapid chess is a must for GM's in the modern days. 

user813: Good chess players who play online prefer quick games like 10sec + 1 or 1 min because nobody can cheat with a computer engine for such short games.
If a player tries to cheat with a computer, in this type of game, he loses the game on time.
After many quick games, these players can maintain this balance easily. Indeed, they train brain to think very quickly. And those who can think quickly can think slowly. Thus, there is no problem playing slow games after fast games.
Moreover, just for your information, blitz game refers to all chess games where each player has up to 10 minutes for all the moves.

user70: They play quick games probably because it's more fun and doesn't take too much time.  Blitz only damages one's tournament results if played to the exclusion of one's studies.

806: <p>If you have been to an online chess server, you will notice that almost all titled players always play quick games (3 0) at a max.</p>

<p>On the other hand, if you go to tournaments, it needs cool thinking and not instantaneous moves. </p>

<p>I am surprised, then how do they maintain this balance? Doesn't playing too many quick games spoil their overall playing ability?</p>
 881: <p>Playing speed chess makes you concentrate more during a match.</p>
 870: <p>Very simple, playing and winning in the faster games such as Blitz  will give them confidence when they play games that lasts days together.</p>
 862: <p>Blitz allows you to collect game experience fast. Blitz could improve you in:</p>

<ul>
<li><p>Quickly test some new moves and get adequate response in a real game.</p></li>
<li><p>Learn moves so that you will waste less time for thinking in a real game.</p></li>
</ul>
 1420: <p>I am an active member on online chess server <a href="http://www.chessfriends.com">http://www.chessfriends.com</a>. I played there more than 5800 games. My stats as white are exactly same as black. I prefer playing 1 minute games,  but sometimes I play 3 minute or 5 minute games. My experience is, that playing bullet or blitz games improve my tactics skills a lot. I have 2300 Fide rating, and I am still able to play 6 hours National league games, without any problems.</p>
 342: <p><em>Who has the time for a nice 30 minute game anymore?</em></p>

<p>Being a titled player does not mean that all of your income comes from chess and that you live a life of luxury (If only! :P). Most titled players have jobs, families, or other endeavors to deal with on a daily basis. As such, it is nice to sneak in a few quick games when there is time to play. This is why it is popular, because it is easy to use no more than 6 minutes to play a quick 3 0 game and then be on your way.</p>

<p><em>Why play one when you can play many?</em></p>

<p>More than that though is the appeal to play a larger amount of games and positions. Playing one game which takes many hours has its place and is great for your chess (I think slow chess makes my Blitz better), but it is still only one opening that was played. In an hour, it is possible to play up to 10 openings by playing 10 3 0 games. Or, if you are feeling in the mood for a good sprint, 30 1 0 games.</p>

<p><em>Experience</em></p>

<p>It is also nice to build those natural reactions. When you play those 10 games in an hour, or perhaps in a week 100 games, then you begin to see positions that can be transposed into, or certain weaknesses in the opponent's position out of experience rather than a keen observation.</p>
 757: <p>When defending his title at the <a href="http://en.wikipedia.org/wiki/World_Chess_Championship_2012">World Chess Championship 2012</a>, Anand defeated Gelfand in the rapid round. He was able to put time pressure on Gelfand in all four games. In the second game with white, Anand played his moves so fast that Gelfand was forced to make moves with very few seconds to spare.</p>

<p>Being able to perform well in rapid chess is a must for GM's in the modern days. </p>
 813: <p>Good chess players who play online prefer quick games like 10sec + 1 or 1 min because nobody can cheat with a computer engine for such short games.</p>

<p>If a player tries to cheat with a computer, in this type of game, he loses the game on time.</p>

<p>After many quick games, these players can maintain this balance easily. Indeed, they train brain to think very quickly. And those who can think quickly can think slowly. Thus, there is no problem playing slow games after fast games.</p>

<p>Moreover, just for your information, <em>blitz game</em> refers to all chess games where each player has up to 10 minutes for all the moves.</p>
 70: <p>They play quick games probably because it's more fun and doesn't take too much time.  Blitz only damages one's tournament results if played to the exclusion of one's studies.</p>
