The famous scene where a soft-drink stand simply vanishes to be replaced by a slip of paper that says "soft-drink stand" is a great metaphor for the insubstantiality of the false time layer. People are basically hypnotized to believe they are living in the simple, peaceful, mindless small-town world of the 50s when actually they are living in a war zone forty years later. It's a metaphor for how people superimpose a reductive shrunken timeline on their realtime circumstances.
There is a dreamlike quality to Dick's 1950s and a certain slow, unreal texture to time itself. We see this in most of Dick's 50s mainstream novels. It may be that we can start reading them as sf, recognizing them as alternate reality stories about a world that only seemed to be--much like the illusory reality of Time Out of Joint or the alternate history of The Man in the High Castle.
Time Out of Joint begins very, very slowly but once Ragle Gumm wakes up to the full extent of the fake reality that has been constructed to keep his mind on the business of solving the newspaper puzzle, "Where is the little green man?", which holds the key to where the lunar colonists' missiles will land, the story quickly races to what some feel is a preemptory conclusion. I don't see this shift as an artistic flaw at all. What better way in fact to show that time has really changed and the nature of reality itself has shifted?
On one level it's a relativistic time shift, in the Einsteinian sense. The perspective of the protagonist Ragle Gumm changes, detaching itself from the collective, and in so doing assumes its own inertial frame with its own altered spatiotemporal coordinates.
Incidents like the disappearance of the soft-drink stand represent a kind of temporal breakdown, in which the character exits the consensual temporal matrix and falls through it orthogonally into an uncharted zone rife with new possibilities and new modes of perception.
But the new frame of reference is not just equivocal or different, it is of a higher order ontologically speaking. When Ragle goes off by himself, alone, at the end, out of the sphere of earth's collective consciousness, Dick is showing us someone who is waking up, experiencing an anamnesis, as he puts it in his Exegesis, or recollection of an original condition that is of a higher order reality. As Dick puts it:
Anamnesis is nothing less than realizing what and where you really are: you perceive the brain and its traffic, you hear the voice of its noös, and you understand the irreality of psyche, world, causality and time.Understanding the irreality of time becomes the preface for understanding the reality of time: how to reveal its truth, not simply transcend it. For there is something in the nature of time--orthogonal, multidimensional time, not false, linear time--that holds the key to higher knowledge, to gnosis.