How to read the roadmap? Some confusion

Hi All,

I was wondering how I should interpret the roadmap. Each segment seems to have a different status: Early development, Review, Implementing, and finally Deployed

Let’s take the Open Ouroboros Delegation as an example.
On december 20th it showed 75% Review and today it shows Early development 10%

How would the workflow be:
Every X percentage Development -> Review -> Development -> Review -> Implementing -> Deployed?

Thanks for the answer!