What's the number 1 most valuable thing that you could spend your time on?
It is learning a new skill? Is it working on your portfolio? What about perfecting that side project you've been fiddling with for a few weeks?
The answer is none of these.
The most critical and valuable thing you can spend your time doing as a creative is getting out and talking to people. All sorts of people. Get out of your bubble. Find some random industry meet ups, or go to a conference. Get out and make yourself known. The only true way to expand your career and your network is to get off your ass and get in front of people.
Of course your work is important. Of course you still need to be obsessed with getting the details right. But that work alone does not a career make.