Q. My editor has added instances of the word that, and I thought it was best to avoid the word that unless it was integral to the sentence. In other words, if the sentence works without it, then leave it out. Am I right or not?
A. Although there are times it can be safely omitted (QED), sometimes that is needed to keep the reader from stumbling: “He gently suggested the plan to escape by means of hang gliders was harebrained.” Unless you are certain how to judge each case, it might be best to trust your editor. See also CMOS 5.212.