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.
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.