As a reader, you get a plot, simple, with a twist, but then it turns again....does a reader like a good twist and turn book? Without it being soooooo confusing obviously that the reader can't keep up? Do you think it thickens the plot????
Of course you must have them. What else will motivate the protagonist to do more than plod along in the same direction? The protagonist's situation should be, "Nothing works and you can't get there from here." And every time the protagonist thinks they have it figured out you change things. Hell, a scene is a unit of tension that begins in uncertainty and ends in disaster. So at the end of every scene the protagonist must go in a new direction. And a reader who is saying, "Oh my god...what do we do now?" is a happy reader.
