Perodicticus potto
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Your link does not say anything about the time food stays in the duodenum. It is not only the first part of the intestines, it is also a very small part and therefore it only makes sense that it doesn't stay there very long.
Like so many things, this "only makes sense" at first glance, but doesn't once you know the whole story.
First of all, food doesn't fall straight through the duodenum like a kid through a water slide. The emptying of the duodenum into the jejunum coordinates with the emptying of the stomach into the duodenum, which in turn is strictly regulated by hormones that are produced by the duodenum itself. One part will empty into the next only when the right stage of digestion is reached.
Secondly, while the duodenum may be relatively small in length, it is lined with projections called villi that greatly increase its surface area.
And thirdly, there is one heck of a lot going on in that space. Much of the digestion that we superficially think of as occurring in the "stomach" actually occurs in the duodenum. It is the main site where proteins, fats and carbohydrates are broken down into their component amino acids, fatty acids and monosaccharides, using secretions from the liver, the pancreas and the duodenum itself.
There is no single answer for how long food stays in the duodenum, because it depends on the amount and composition of the food -- also, different components of the same food will not necessarily travel through the digestive system at the same rate. But it is not a lightning-quick process.