I usually don't make too big of a deal about it, but with the UBS6 and NA29 coming out soon, it might be a good idea to rethink the use of square brackets in the text. I can see how some people would prefer to have square brackets in their Greek New Testament. But they're just not for me. I guess I feel that if you consider that a word/phrase/verse or whaverer is not in the original written by the author, you don't need to put brackets around it. Place it in the apparatus where it belongs. However, if you see brackets and go "That's amazing!" then I'm happy for you.
Here's a place where brackets are probably unnecessary.
The words "in Ephesus" (1:1) enjoy early and widespread attestation. They seem to be original despite the letter's absence of any personal greetings.
Have a wonderful day!