I think it depends on what you want to achieve, Derek.

If you are providing dry, educational information, yes it's best to stick to one niche and be the go-to person for that topic.

However, sometimes writers/creators have an interesting personality and that is what attracts the audience. In that case the niche is "you".

That being said, in line with your title, sticking to a niche at the beginning will likely help you grow your account and gain more visibility.

And congrats on finding success in your own niche!