Just had an insight, as a classic procrastinator.
Procrastination is often attributed to fear. To perfectionism. To "finishing" something and then finding it isn't good enough. To fear of disappointing or letting people down.
I have to write a simple 500 word summary for someone, and I've been faffing around not finishing it for days. Even though I've been writing more than 500 words in spontaneous answers on Quora etc. during that time.
It's not that I'm more interested in the Quora answers than the thing I'm meant to be writing. The answers are interesting, but so is the piece I'm meant to write.
Why is it so much easier to write unsolicited Quora answer than something which is required by a friend and my career?
Maybe it's the unsolicited. The answer is that there's something about the two-way transaction that is uncomfortable. That raises all these issues of requiring finish / perfection. That raises the potential for disappointment.
Unsolicited answers are pure gifts.
So perhaps procrastinators are people who are natural citizens of a gift-economy. Uncomfortable with the promises and constraints of exchange. But happy to work on spontaneous gifts.
Note it's the spontaneous / uncommitted that's the important thing here. NOT the unpaid. Procrastinators are not necessarily better motivated by voluntary work if it still involves making promises.