WJP wrote:In the guidebook it is stated that "...even a 20-minute phase is unheard of."
I just read chapter 6 of Robert Monroes first book 'Journeys out of the Body' again. There are episodes of whom Monroe says that the 'out of body' journey lastet more than one hour, the longest episode lasted three hours and fifteen minutes, as Monroe reports.
These were journeys just after the beginning of his experiences.
it depends on how to measure the time... If you have the phase that leads to normal sleep (slow-wave sleep) and then you have a second phase within same picture (scene), there is an illusion that the phase is uninterrupted. Even if you compare the time before and after sleep.
To prove the phase duration someone should monitor the brain activities, using EEG, fMRI, etc.