Will blitz help more than standard time control to improve my chess
No. Standard time control chess always helps more to improve your game than blitz chess because in standard chess you spend more time analyzing the game.
Chess is a game of intelligence but even more so of knowledge. The more (structures, endgames, openings, etc.) you know, the better you are.
To make a rather primitive classification, the average grandmaster
knows about 1,500 - 2,000 typical positions, including the opening,
possible middlegame plans, and some outlines of endgame. Super GMs,
like Kramnik or Anand, have a wider and deeper knowledge. As for
Kasparov, his knowledge is truly head-spinning, I guess, his number of
positions might exceed 10,000. Garry's memory is phenomenal! I think
it even impedes him during the game. - Valeri Tsaturian
Knowledge is hardly acquired in 3-5 minutes (blitz) and even if it is, it is quickly forgotten. To gain chess knowledge, you need to spend more time studying the game.
The more time you spend studying a position, the more you understand it, the better you remember it, and the more insights you gain into it. It also helps you correct your faulty decisions in the post-game analysis, because, if you're wrong, it can show you to what extent you're wrong in your judgment of certain positions.
For example, I played a game recently in standard time control and in one position, my opponent was really surprised that I didn't capture his bishop with my knight. During the game, I thought that the trade of bishop for knight wouldn't help me in that position, but in the post-game analysis, my opponent proved me wrong and demonstrated how it was good for me. I went home and analyzed with a computer and found that my opponent was right. If this had been just a blitz game, I could have just excused myself saying "well, I didn't have enough time to consider the consequences of that" and thereby prevented myself from recognizing this flaw in my own knowledge.
If No when and for what purpose should i play blitz?
You can play blitz to
1) Enjoy yourself.
2) Check your opening preparation.
3) Develop a rough understanding of certain types of positions with the intention of analyzing them in depth later. This third point is crucial, because it is the best way to use a blitz game. You may not learn much during and immediately after the game, but if you analyze your blitz games, you will still learn a lot.