The folks who urge haste occasionally need to be reminded that there is nothing faster than doing it right the first time.

That said, finishing (not just working) quickly is very important. You will never get good if you do not finish a lot of things. If you need to iterate to a solution, you will never finish if you do not iterate quickly.

My corollary to "good, fast, cheap: pick two" is that there's no such thing as good, slow, and cheap, and if there were, it's booked for the next 30 years anyway.