i think blitz might be the fastest way to get better

this way you can make as many mistakes possible and learn in the shortest time

I think rapid or classical, as we can think more in it . But after you get better at rapid you can shift at blitz.
I did the same thing

Also the quickest way to develop terrible habits that will take even longer to un-learn

Blitz might be the fastest way to get better at the openings but nothing more.

It's not a bad training's tool. Not as bad as the old myths indicate.

Rapid seems like the best option for improvement for most people. It's a manageable time commitment, but still long enough to require calculation.

Blitz is the fastest way to make mistakes. But it takes awfully long to sort them all out in order to learn from them!
Say, you make 7 mistakes in a rapid game, you can analyze these and learn. But if you play 3 or 5 blitz games instead, you make 50 mistakes and you will not take the time to analyze them 50 and learn from them. Instead you will maybe learn from the 10 greatest of them, while the 40 smaller ones get lost or grow into your blitz habits, your habits from blitz.

As long as you understand that the clock management is also a skill that has to be mastered, yes.
Some people enter in panic mode way too fast when they get low on time.

@POSITIVEVIBESONLY said in #1:
> this way you can make as many mistakes possible and learn in the shortest time

That my friend would be ultra bullet. Not Blitz.