As a scientists, I'll never classify the 200 intermediate steps as "major breakthrough". Perhaps 1 or 2 of them. Fusion looks difficult, so let's say 5 of them. All the other are just improvements, minor improvements, side quest, dead ends, easy task for a undergraduate thesis, ...
If you read "breakthrough", you can be almost sure that it's an exaggeration from the press or the marketing team of the university (and in some rare cases, from the research team).
