Aside from not having a focus, another pitfall a lot of bloggers fall into is inconsistent posting. How much posting is required to be consistent? This is another one where I use my go-to reality check: how would I react. If I came across a blog that was last updated three years ago, I would probably think it was inactive. Three months ago? I would probably think it's on the back burner. Three weeks ago? Forgivable if the posts are long and thoughtful. Three days ago? Acceptable. But this is me. Think about how you would react.
That said, posting consistently encourages traffic. Even if people are interested your posts, they are not going to turn into loyal readers if they feel like you don't care about the blog. A blog should ideally be something that your readers look forward to reading on a regular basis. Like the daily comics or something. If you didn't know when the comics would next be published, you'd probably just forget about them.
But blogging should be fun, not life-consuming. Making blog writing part of a day's routine can help. More importantly, embrace the idea of scheduling blog posts. Scheduling blog posts is usually a post setting option. That way your whole day does not have to revolve around getting back the computer in time to make a post. It also means that you can sit down when you have time and crack out three blog posts and space out the posting over the course of the next week or two.
The number of posts you have written does affect a blog's popularity. But an active looking blog will always look more attractive to new readers over an inactive one. Therefore, if you write three posts in one sitting, it is far better to have one post every week for the next three weeks than just posting all three at once.
This also helps with the pacing of your ideas. But more on that later.