Absolutely no data is given to back up this assertion, and even if data were given in some research, it would be some kind of average value, selected from a sample size of, say, 20-25 year old, disproportionally male Californiamen, who all studied at the same university, and were all willing to donate their time for some undergraduate research and obtain 50 U.S.D. in return, and the data would already reveal immense spread and variability with clearly around 40% at least heavily increasing productivity by switching, but the article would stress that the average would not, and thus advocate that no man so “context switch”.
Yes, practicing batching will make one more efficient at it, but practicing context switching will also make one more efficient at it,and the true reason is that many tasks require one to wait for something else and do nothing.
The reason why I'm already washing many of the dishes I cooked with as I cooked is of course simple: there is nothing to do except stirring once in a while at a certain stage in cooking so I might as well use that time to do something else.
I also took various sips of my coffee writing this, not because I had nothing else to do, but because it tasted nice.