What is the optimal length for a blog post?
I have no idea. I tend to keep mine to around 500 words long because I read, many moons ago, that on the internet people's attention span is measured in nanoseconds, and so readers cannot cope with anything that will take longer than a minute or two to get through.
But as it happens I like reading long-form content, ie content of several thousand words, and I read somewhere that 5,000 words plus is the optimal length for getting a post shared on social media.
Then again, I enjoy short, snappy articles. Lo and behold, I read somewhere else that short, snappy articles are the best thing to do to gain traction quickly.
In other words, nobody knows.
I had a similar revelation years ago when I was studying Hamlet at college. I read and made notes on every piece of literary criticism about Hamlet I could find. Then one day, while making notes on the 13th essay I'd found, I suddenly thought to myself:
"These people don't know any more about Hamlet than I do. They all say completely different things from each other, so I'm assuming they can't all be right. They draw on "data" to prove their points -- but I get the impression they selected the data according to the view they already held. My opinion is just as good as theirs."
And with that, I stopped reading lit crit essays, and I never looked at my notes again. I passed the course with flying colours.
Here's the bottom line for me: write the length that is a combination of what you need to get your point across without rambling, and what you feel comfortable with. The worst that can happen is that you end up with no readers -- but you'd have had a great time writing, and honed your craft in the process.