To me it seems that the balance of social and alone should be to result in inner peace. This is to ultimately increase productivity in doing what you find satisfying in life.
I write code a lot at work and we plan it out in a group then move our own ways to write it with occasional instant messaging about this or that. But sometimes when I am writing I can't focus or have trouble getting myself into the problem. And from there I find that reading or talking to someone at the office can help put me at peace and ultimately help me focus on the work I have to do.
Like right now I am at work and writing this - I have a task to do to document some things but I hardly remember them and I need to do something that is going to interest me. Am I alone while doing this? Well, sure, I am available for other people to approach but I am not trying to talk to anyone.
I think the term alone is relative to our sense of privacy. If I was in a room with the door closed would I feel more alone than if I am sitting in an open office? Probably. But if I can get to a peaceful state it will probably produce similar results in my work ethic/productivity.