Two posts can cover the same topic and do completely different jobs. Basia Kubicka's split is the cleanest version of this I have heard. A reach post is how to do X. Anybody could have written it. That is precisely why it travels, because a generic guideline is not attached to a person, so sharing it costs the sharer nothing. An authority post is how I did X. Same topic. Same lesson. But now the thing being shared is you, which makes it much harder to pass along and much more useful to…