Marketing is just a sales strategy.
I think if you want to sell a game on existing popular IP, high end visuals, a celebrity actor, you can put out a shorter trailer and they pop at something like the Games Awards. I think if your game is difficult to understand immediately, not cinematic, gameplay and systems driven, it needs a longer demonstration to explain it like Starfield or Breath of the Wild. If your game is too small to even have a budget for a main event, getting shown at all in a sizzle reel is still better than nothing.