A mix of both. Short games are good for getting in opening practice and being prepared for time scrambles. Long games are good for developing your analysis skills.
Short x Long games to improve at chess

When you're beginning, it's important to get in a lot of games. The need for experience trumps quality to an extent. (The longer the game the more practice you're getting).

15 min. games in general are my favourite. The calculations mostly go down the drain when I have to rush (hello my name is doctor Obvious) seeing as I'm not all that accustomed to the whole clock thing yet. Whatever floats your boat, I guess.
I got the whole 15 minute idea from leafing through Bronsteins book "The Wizards Apprentice" where it is mentioned that 15 min. is a good basis for a friendly game.

A mix of both. Short games are good for getting in opening practice and being prepared for time scrambles. Long games are good for developing your analysis skills.
I agree. A friend and I like to play without a clock and letting each other as much time as we want. For me, that truly develops my analytical skills. And, over the years I have played in all types of environments and noise levels, which I believe has helped me concentrate without being easily distracted. I also enjoy playing on different types of chess sets, too. I doubt that has any value in improving my game, but it keeps me alert as to which piece is which, and in turn, exercises my mind. For serious play I prefer Staunton sets.

Nice. I tried the other day to play a long game. I couldn't. All my moves had a 1 minute maximum time out... I'll try to do better next time. I will be in a tournament next weeks. Let's see how it will be...

You learn alot more of long games. Dont forget to analyze it afterwards, and if you lose, find out why you did lose, and make sure you never make that mistake again. Thats how you get better, and you cant really do that with short games.

It depends on what you want to play - if you want to play long tournament games, you should concentrate on long games. If you want to play blitz tournaments you will have to play blitz because even if you are a very good slow player, if you never play blitz you will be too slow and lose on time a queen up :)
Personally I keep it with my working schedule - blitz and tactics trainer on weekdays, long games and chess books on weekends, I think that's a good mix.
Hi. I'm new at chess. I've been wondering? Is it better to sharp our mind to play a lot of short games or a single game very deeply calculated?
I try to play everyday some games. Not sure how many, but all of them are short ones, like 10 minutes TOTAL game (even playing in 15 minutes games, it often ends when both players reachs 5 minutes).
So my question is that: to get better at chess, is it worthy to play several short games or a single game very deeply calculated?