Some people have been making this statement: “The attorney just keeps talking in run-ons.” He said, “We were together, AND she seemed to be distracted, BUT I didn’t say anything to her at the time. AND it was beginning to be irritating, BUT I didn’t want to cause a scene.” When people go on and on and decide to insert and or but between all the sentences, those are NOT run-on sentences.
(And if your question is how many of these to string together before putting a period, the answer is probably no more than four at the very most! It is best to have two or three, and if any one of the sentences is long, then it is best not to put it together with several others.)
And our point here is that run-on sentences are created with bad punctuation. We don’t “say” run-ons. We create run-on sentences by bad punctuation.
A run-on is two independent clauses that have no conjunction between them and are put together with a comma or no punctuation.
…Mr. Andrews took over in May, he came from a rival company. (run-on sentence)
…She had curly hair he had straight hair. (run-on sentence)
These sentences need a period after the first sentence.