When I was in school, I was taught to always begin a new paragraph after a quotation or after a speaker concludes a segment of dialogue. However, in recent years, I have seen authors abandon this rule, continuing a scene's description after a quotation. To clarify, I'm not asking whether I should create a new paragraph when changing speakers. Rather, I'm asking if a paragraph such as:
Joe said, "This is a placeholder sentence." He wrote the same statement on the chalkboard.
is correct as is, or if the second sentence should begin a second paragraph.