Specifying the remote and branch name again when doing a `git pull` is not necessary after you've set it as the upstream branch (which the `-u` option in `git push` did in your example).
To play devil's advocate, I purposely never use push/pull without specifying the remote and branch because doing otherwise would cause issues if I accidentally forget which branch I'm on (which isn't super uncommon for me, as I've unfortunately gotten so used to seeing the branch name as part of my shell prompt that I don't notice it unless I actively look at it). I believe there's even an option you can put in your .gitconfig to enforce this.