I've met people who were still interested even if the posts were a bit older. Or have people with similar interests reply as well. Am I bothering anyone, @NPM?
As everyone already mentioned, ideally, it is advisable to go for a single niche and get specialized in it, for authority in the industry. However, if the audience for it is too small or too diverse, it's okay to go broader. At the end of the day, there is no rule, so what works for some might...
Well, both approaches have their own pros and cons so I believe you should choose based on your audience, resources, and goals. I prefer to be as niched as possible as it builds better authority and its easier to vibe with your audience.