If someone starts out as a junior designer and keeps practicing, what are some benchmarks to show they have progressed as a better designer?
As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or specific expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, see the FAQ for guidance.
If you are asking for within the realms of UX, then UX Design Practice Verticals can be a good measurement for you.
Its a grid, made of eight columns standing for main domains in UX, and six grades of depthness going from practical to strategical areas of practise. It was introduced at UXmatter article The T-Model and Strategies for Hiring IA Practitioners, but explained solely for Information Architects. Nevertheless, it matches Visual Design either.
I like this approach, because it has well thought categories and shows the differences as well as overlaps of each specialist in the field of "Computer Design". And it gives a sort of guidance, where to grow and what to leave aside.