There are, broadly speaking, two motives for blogs: 1) writing things out to clarify your thoughts on something, or make notes about how you did something to r

There are, broadly speaking, two motives for blogs: 1) writing things out to clarify your thoughts on something, or make notes about how you did something to refer to later, or otherwise for your own purposes, and then once it's written why not share it as long as it's easy 2) writing things for other people, to reach them (to persuade, to get hired, etc.) For purpose 1, do what's easier, which is probably one blog. For purpose 2, the SEO hit matters more, but you say you don't care too much about that. BUT, what you don't want to do is combine them, and then spend a lot of time trying to make them completely separable, and some of what you mention planning sounds like doing that. It can actually end up being more trouble than just having separate blogs. So, if you want to combine them, great, but beyond some very basic tagging or searching (if it's super-easy), don't try to keep them separate, on one domain. If you want to do that, it's probably a sign that separate domains is the right way after all.