Depends on what you're optimizing for. This post is about being at the beginning of your freelancing career when you're trying to figure out what's going to keep you going. I found that after 13 years of consulting I finally pick a niche. When I did marketing, sales conversations, and execution became a lot easier, and effective hourly rate skyrocketed.

Picking a niche is smart if you know it'll sustain you on the dimensions that matter (emotionally, financially, intellectually, etc).