I'd say it doesn't help your F2L more than... let's say driving a car.
Sure you might look ahead to see what the next piece will be, but this only absolutely necessary at the very last levels.
While you're driving a car you will also have to look ahead, or else you will run over an old lady crossing the road when you are making a turn in a situation where the view isn't clear.
Same goes for pretty much any activity where you are "looking ahead".
Well, not if you are playing speed tetris.
I have never played "speed tetris", but I assume it's just a really fast-paced variation of the game.
And that's pretty much why I wrote this;
Sure you might look ahead to see what the next piece will be, but this only absolutely necessary at the very last levels.
Also, consider this:
Would it be safe to say that you would get better at F2L if you were to triple your speed while driving? I mean, you would have to look pretty far ahead to check for possible road crossings or red lights
Does this help my point? I doubt it.