Things you might not have known about Google Authenticator:
Copy and paste
If you press and hold the 6-digit number, it puts it in your cut and paste buffer.
Re-order the list
If you click the pencil to go into edit mode, you can change the order of the items.
I find this particularly important because I now have 12 different systems authenticating with this app, and only 4 fit on the screen of my tiny iPhone SE.
I've pushed the ones that I use the most to the top of the list. The Google-related services that generally authenticate via a notification asking "Is this you trying to log in?" are now all shifted to the end of the list, since I rarely need them.
As a result, I am able to authenticate in about half the time.