Aristotle notes that a string of unconnected speeches, no matter how well-executed, will not have as much emotional impact as a series of tightly connected speeches delivered by imperfect speakers.
The concept of plot and the associated concept of construction of plot, emplotment[?], has of course developed considerably since Aristotle made these insightful observations. The episodic narrative[?] tradition which Aristotle indicates has systematically been subverted over the intervening years, to the extent that the concept of beginning, middle, end are merely regarded as a conventional device when no other is to hand.
This is particularly true in the cinematic tradition where the folding and reversal of episodic narrative is now a commonplace. Moreover, many writers and film directors, particularly those with a proclivity for the Modernist or other subsequent and derivative movements which emerged during or after the early 20th century seem more concerned that plot is an encumbrance to their artistic medium than an assistance.
See also: plot device