In both the Wings of Liberty and Heart of the Swarm campaigns there are research options for automated refineries/extractors, which allow vespene gas to be harvested without a worker. This has obvious benefits, such as freeing more supply for combat units and allowing long-distance vespene gas harvesting, but I'm curious how fast the gas actually collects.
Assuming the command center/hatchery is as close as possible to the vespene geyser, will three workers harvest gas quicker than, slower than, or just as quickly as the automated building?