It does indicate progress, but as this informative article explains - there's much more to observe than an opening cervix.
Here's a quote from Midwife Thinking, Vaginal examinations: a symptom of a cervix-centric birth culture.
The truth is that women’s bodies are complex, unique and immeasurable. Birth is a multidimensional experience that cannot be accurately defined by anyone outside of the experience. We – those of us who give birth and/or attend birth – know this.
Let's not oversimplify birth or try to put it on a neat timeline.
What's been your experience?