How to assess your own skills?

I used to assess my skills based on these parameters, but they might be slightly shallow measures for a seasoned dev.

Quality: Is the quality of your current project better than the quality of your previous project?
Time: Did you accomplish task X in time Y when previously you would have taken time Z to accomplish X ( where Z>Y)?
Design: Are you able to structure your code better than you would have before?
Errors: Is the average number of mistakes you commit on a decline?
Clarity: Do you have greater clarity in your thought process while taking on a problem?

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