The general wisdom is that it is better to only ever use channels 1, 6, and 11 as they are the only three non-overlapping channels for 2.4ghz wifi (in the US), and two adjacent networks on the same channel would perform better than two adjacent networks on different (but overlapping) channels.
So then, why would the IEEE even allow for 11 channels in the specification? Is there any possible use case where it would be desirable to use one of the in-between channels? Even if you were completely isolated from other networks, it wouldn't make sense to use other channels because you would then be limited to only two, rather than three non overlapping channels/access points.
I have read many articles explaining why its better to stick with 1, 6, and 11, but I have yet to come across any explanation for why they didn't just make three channels to begin with (1, 2 and 3 mapping to 1, 6, and 11 respectively).