Potty training a boy in a single day may sound far-fetched, yet there are many people who swear not just that it can be done, but that they themselves have accomplished it. This may indeed have occurred, but there are also many who think the results are considerably exaggerated. For example, some sites claiming to teach people to potty train in one day mention the accidents that will occur after the big day is over, but reassure the parents that the child will be free of accidents within two weeks. In other words, they'll be fully trained in two weeks, not in one day.
The basic idea of potty training in one day is that you tell the child in advance that this is the day he'll stop wearing diapers and start wearing "big kid" underwear. You devote the entire day to your child, plying him with his favorite food and drink so that at several points during the day, he'll need to use the potty.
Each time, you take him to the bathroom and he learns how to do his business there instead of in a diaper. You train him intensively, perhaps using visual aids as well, like picture books or a doll. By the end of the day, he is supposedly potty trained.
Between reviews of one-day training books on www.amazon.com, or comments on websites that encourage people to potty train by this method, it appears that sometimes it works, and sometimes it doesn't. When it works, the parents are understandably grateful and enthusiastic. But other parents report that their children became unhappy, even to the point of feeling ashamed, or feeling like they were in trouble all day. These parents didn't feel that potty training kids using the one-day method helped them, and their children sometimes even grew afraid of using the bathroom.
What does all of this mean for the idea of potty training in one day? The results seem to indicate that the method will work for some children, but others will have to potty train by more conventional methods that take longer. Everything depends on the child's temperament, and just as no child is temperamentally the same, there's no "one size fits all" method for potty training either. It's up to the parent to choose the right method, based on their child's personality rather than on what would be most convenient for the parent.