I'm not fantastic as blitz, and yet it can be good as i've read here in similar threads, but generally only for shaking chess rust off a player, generally, long games are better. I myself have noticed when I played some bullet and blitz after a coupke 15 minute games, I did ok, but after bullet, when I tried to concentrate, my thinking was shot.
So generally I would say a rule of thumb is play what will allow you to do some high level thinking, but will at the cost, later force you to play against time pressure, while i'm no coach it will help you keep your cool in longer OTB ganes when you do get into pressure, and probably help streamline your thinking process.
A final tip of mine would be if your too impatient to play complicated games yourself, try unclear or imbalanced (knight for bishop) solitaire games (Games played by masters where you try to guess their moves) give yourself 15-30 minutes per move then pick your best choice when time is up, then look at what the master played. It may also be useful to play your moves against a strong computer so even if you make a mistake, you can keep going in the position, additionally, it may help you understand the position better depending on what, and how the computer plays vs the masters.
blitz helps you realize tactics and strategy much quicker, and also helps in case you're in time pressure in an OTB game. Just be careful not to play too fast in an OTB game
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