I’ve found that if you want rough indication of a designer’s experience, look at the time they spend on different stages of the design process.
Novice designers spend most of their time creating a solution, and maybe 20% refining it.
Intermediates split the time roughly evenly.
For senior designers, the ratio flips: 20% creating, 80% refining.
And the experts realise that creating and refining are actually the same thing.