[flaviocopes]

I don't think it's mandatory to write about novel or innovative things. It's your blog, you can write what you want.

Agree with the write for yourself mindset.

I am kind of doing the same thing on my blog https://flaviocopes.com where I write every single day (personal challenge) about some particular thing related to Web programming, and I mainly write for me, because I don't have a good long term memory and every time I need to use X I reference what I learned n months ago about it. That's much better than searching again and again "that post" you remember that clarified the thing for you.

Turns out this is useful for other people too, as I can see in the positive feedback I get.

After some time I started rewriting old posts to improve them / add more things I learned, as your writing style evolves.

So, my advice is, just start and stick to it.