People think this about 128 in Massachusetts, too, but generally what I observe is that people leave my "empty space" about as often as they enter it. I leave a big empty space for safety reasons, and also because I actually understand how inefficient constantly accelerating and braking is. I'm usually able to maintain it without too much trouble.
Whether or not it actually helps traffic, I couldn't say.
This seems like it'd create a danger if you're actually adhering to your goal of maintaining the "empty space": as soon as someone pulls into that space in front of you, you no longer have an empty space, and the only way to restore it is by slowing down to allow space to open up again. Which, as repetitively and suddenly as you'd have to do it, would pose a hazard to traffic behind you.
The typical solution to that situation is more like "Wait 30 seconds. The person who just pulled in front of you catches up to the car in front of him, and moves out of the lane to get around."
In the rare situations where this doesn't happen, I usually have a longer space than I actually need, so I just eat the difference.
Whether or not it actually helps traffic, I couldn't say.