Should you not use Libby? Go ahead. You already paid for it.
I just don’t use it frivolously. I try not to use Libby to borrow what I might not actually read/listen to/use. I try to make sure I have the time to read what I take out.
I use the preview feature.
The point is, the marginal cost to the library of an additional circulation of an ebook is significant, not trivial, up to (if the library decides not to renew the expensive license) loss of the ebook to other borrowers. So be mindful.