It really depends on the individual. For some, their extracurriculars are exceptional; for others, it's more a "casual" thing.
It's really a matter of personal judgment - regardless of work vs. extracurriculars, you want to play to your strengths. If your strongest and most compelling examples come from your work, then don't feel you need to mix it up for the sake of mixing it up. Conversely, if most if not all of your most compelling examples are outside of work (and you feel your resume can pretty much sum up your work), then don't feel compelled to write about your work.
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