In publishing quotes MLA and APA both give a word count - 40 words can be included in quote marks, longer than that should be a blockquote. I don't count the words often, I use just the blockquote because it is generally understood to be quoted material (and you don't use quote marks WITH blockquotes). Other style books give similar rules, but these are the two I work with most. The italics in the blockquote below are for emphasis of a quote within a quote (and I preferred italics to bold that was originally used.)