Every time I write a post for my blog, I ask myself this question:

What if the majority of my readers already know what I'm writing about in this post?

I've purposely held back on a number of ideas for blog posts in the past due to this. I get myself into the mindset that the idea for the blog post will be invaluable to the majority of my readers and therefore I dismiss the idea.

However loooking over my analytics for previous posts I have written that I have questioned but went ahead with, I have been surprised by the number of times the posts I thought would quickly disappear into the archives are still being read by more than a hanful of people every day. Even though I had the belief that the post would only be relevant for a limited time and to a limited number of people, these posts are still drawing in new readers every week.

So my advice to you is this. Even if you think your readers won't find any value in your idea for a blog post, write that blog post anyway. Chances are that someone will find value in your blog post rather than no-one.