I know why I have - the logic for doing this was pretty clear and it still applies. I use this blog for two things. Firstly, to continue developing and sharing my thinking on HCM from my book (although you'll still find a lot of great content there). And secondly, it's my general professional blog, ie it's where I share a bit of information about what I'm doing, where I'm going etc. Hence, Jon Ingham's HCM blog.
My second blog is much more focused on social capital rather than human capital, and is more about supporting my learning rather than sharing my knowledge. And it's for collecting content that I hope will inform my second book. This is my New Social Business blog.
But sometimes, actually quite often, I have a real dilemma about where to post. Take this one - a review of an event on reward and inequality. I've posted it on Social Business because it includes some thoughts about increasing social cohesion within Britain (the points will apply to the US too), and which can, by extension, be applied to organisations too.
But the reward theme will potentially apply to a lot of readers of HCM as well. So, anyway, if you think you might be interested, take a quick look (if you use a reader, the feed is http://feeds.feedburner.com/Social-Business).