Ask HN: Time management skills that don't rely on timekeeping

It seems to me that productive people get things done regardless of time constraints and unproductive people never have enough time. I am interested in the techniques used by people that get things done and their mindset.

Prior to clocks and time keeping, there was no sense of I've been working on this for too long - this is a bit naive. But I'm sure the productive people for millennia ago share traits with modern day productive folks.

What are those traits? And can they be cultivated?