There is one reasonably common daily event that autistic individuals describe as extremely taxing -- the "quick stop on the way." Perhaps Mother suggests they stop to get milk on the way to pay the property taxes. This interruption while running errands may result in "a complete meltdown" and even an "inability" to continue toward the original destination.
Why does this seemingly small event cause such stress for the autistic individual? Some on the spectrum explain that being in the community is always stressful, and the addition of "quick stops" increases the existing tension. Others add that the stop, no matter how brief, is still an unexpected change from "the plan." The ASD individual prefers to know what is going to happen next, and shifts in the plan can be very stressful.
What doesn't seem to help the tension is to "explain" why the stop is inconsequential. "It will only take a minute," or "I just have to get eggs so I can make Suzi's birthday cake tonight." A rational explanation does not make the interruption easier to bear.
One helpful approach may be to suggest that the ASD individual wait in the car. Removing the element of actually entering a business or store may create some relief. Additionally, bringing earphones or other distracting activities may help the autistic soothe while waiting in the car.
Adapting to unexpected changes, leaving the house, and engaging in the community are each stressful for the autistic individual. Combining all these challenges by adding "quick stops" can be the tipping point for a meltdown that hijacks the rest of the day.