There should not be such a thing as a waste of time when you are a freelancer. Particularly a freelance writer.
Yes, I know, all freelance writers know. The waiting game is no game - you just have to make it useful time instead of a waste of time. Unless you get some form of a permanent contract. But then, ask yourself: why did you go freelance in the first place? Unless, of course, you had no other choice. Then it could turn into a real chore. With a lot of waiting.
If you think you’ve learned all you need to learn or that you’ve turned all the work sites in and out, you haven’t. Something new turns up every day. I know from personal experience.
Looking at sites and advice from other freelance authors is one way to make your time useful. You can always pick a new hint, place to look for new work, or any sort of useful information.
Ok, so most of those sites sell something, for real money or just for those clicks only Google, Alexa or whoever else is measuring can pick up. And yes, your mailbox will spill all over your computer, they all ask you to subscribe.
But then think of it this way - copywriting is a job of selling anyway, and we all have a level at which we can be reached to buy something. If we have the means to buy it. Or out think of it the way Frank Zappa responded (and recorded) his response to a person in a crowd at one of his concerts: “Everybody in this room is wearing an uniform, so don’t kid yourself”.
In the end there is one question you have to answer. Can you, and how much you can resist the selling pitch. At some point, you won’t, even if the money is short. But then, you will be gaining something. It can be a new knowledge, a tip, a site to seek more work or just a realization what your threshold of resistance to a sales pitch is. And that definitely does not fall within a waste of time.