Your article states: "Headlines should be about 70 characters, but not more than 80 characters in length." Please note that this refers to Meta Titles not headlines. Headlines can be much longer, while Meta Titles should be maximum 65 characters, although one should test how the Meta Title / Description will be displayed: https://totheweb.com/learning_center/tool-test-google-title-meta-description-lengths/
Your article states: "Headlines should be about 70 characters, but not more than 80 characters in length." Please note that this refers to Meta Titles not headlines. Headlines can be much longer, while Meta Titles should be maximum 65 characters, although one should test how the Meta Title / Description will be displayed: https://totheweb.com/learning_center/tool-test-google-title-meta-description-lengths/