Why do you rarely see companies looking for part-time developers? It seems like if you hired a developer for 20 hours a week, you might be able to get the 20 most efficient hours from that developer but still only pay half the going wage. Additionally, you wouldn't incur the benefits costs of a full-time employee. Are there any good examples of this being attempted?
It would be harder to extract unpaid overtime, coordinate meeting and facilitate cross training. Not only that, but it's more difficult to manage and allocate folks when there are four 1/2 time workers instead of 2 full timers.