A lot of you ask... How long does it take you? The answer is that you will never know as i do not know the answer myself.
All i know is that i get into a piece and i keep at it for hours and hours with no specific idea of time. When i get out of trance is when i realize that i have to eat or take a break from physical pain (hand and back due to work)
This is when i have a better idea of how much time i have spent working away. But i never think about it.
Time for me as never been an obstacle of an important detail into my work and life. The time it takes to get to a goal, point or finish line differs from one person to another.
For me, i really don't care. I just keep at working at it until i feel it is over.
Time is what life is. I work with it.