The term is one from British English. It is not really used in USA.

I can't say if the idiomatic expression "in fits and starts" is common since it might be a common expression in some countries while not in others. However, I have seen it used in a few places. It's basically an expression used to mean something that happens irregularly, or in irregular or inconsistent intervals. For example: 1. She wasn't very fluent in Japanese. She spoke in fits and starts. 2. Technology isn't something that you can force to evolve at a regular pace. It advances by fits and starts.