whether that's a part-time diploma or a complete reversal of direction and a whole new qualification/career etc, what has your experience been? I'm not talking about essential professional certifications, but more when you've done all the study you *need* to do for your work but you voluntarily do more for interest or cv boosting or whatever.

If you have, was it ultimately worthwhile, or just a good idea at the time which turned out to be a bit stressful or a bit of a waste of time/money?