My opinion is: sleep at least 2 hours at a time, of course, noon nap is not counted.
Because people need 1- 1.5 hours to enter deep sleep, and deep sleep is really effective sleep.
The legend of Da Vinci's sleep method is just a legend. According to my estimation, most people who practice polyphasic sleep belong to sleeping for about 2 hours at a time. Because if a person's sleep quality is not high, he may not have any deep sleep all night, just like wasting time lying in bed.
And those who are successful, by adjusting their sleep patterns, let themselves go straight into deep sleep when they want to fall asleep. It will save a lot of time to wake up if you sleep too lightly. And the effect of sleeping is even better than sleeping for a night! Because probably many people seem to have stayed up all night, that is, they have not entered deep sleep or basically have not entered deep sleep.
In addition, this state is best done at night.
Because humans and primates are diurnal animals, they start to move at dawn. Of course, they can take a nap during the day, but they don't really sleep. So it's best to use the evening time.
Tell me another experience of my own. I belong to the kind of person whose thoughts are active at night and whose creativity is greatly enhanced. But in order to live a normal and beautiful life, I am used to squeezing out the night time-sleeping.
Because personally, I almost never take a lunch break, which has been the case since I was a child. Very energetic. However, sleep is not very pleasant since childhood, and the greater the pressure in adulthood, the worse the sleep.
So I thought of this method.
In addition, I think it is best not to set the time too "periodic".
It seems that some celebrities are very emotional: when they are tired and sleepy, they can go straight to an efficient deep sleep.
You have to find a cycle that suits you.