I take issue with lists like these, prescribing ways for me to make the most of my time as a young, reckless, seemingly-invincible 20-something. Not only because their tone is not unlike that of a parent telling you for the ump-teenth time about the Good Old Days, but because it's purely subjective advice presented consciously as objective truth.
In my opinion, the one way one should take advantage of one's 20s is to do whatever you want, for better or worse. The last thing I want to do is look back on my 20s and realize I didn't do something or have an experience because someone else decided it's a waste of my time. I have no real responsibility to anyone but myself right now ,and it's up to me to make decisions, good or bad. Granted, I don't advise anyone to make catastrophic decisions for the sake of 'having the experience', but I do advise people to think for themselves.