The goal-gradient hypothesis describes how people (and animals) tend to increase their effort to reach a goal when the distance to the goal decreases. I remembering learning this a study skills class in 7th grade - interesting what sticks, isn't it??
I was just thinking about this as I work on the crocheted table cloth. Having "only" 20 more rows to go has certainly motivated me more to work on it with better consistency (when in reality, 20 rows at this circumference is still a lot of crocheting). When I'm close to finishing a woven piece, I'll stay up late or work longer hours than usual to see it through to completion.
I used to think that this only worked for goal-oriented individuals. But perhaps it's more widespread than that, unless there is a competing influence of neurotic tendencies to avoid completing things. Then there are the various theories in goal system studies, and the variety of goals such as focal goals, background goals, and context. (Hmmm, how quickly my psychology background rears its head.)
All of that quite aside, the simple fact is that when I get closer to completing a project, the more I want to work on it. It was true in 7th grade (probably why I remembered it), and still true today.
A long way around to saying I'd rather be crocheting than weaving at the moment, so I have to plan out my days here on the island so that I get both done.