From what little I know about Phowa when you are doing it during your lifetime you aren't actually ejecting your consciousness as much as making sure that everything that would support that ejection is in working condition. Think of it like a guy being shot out of a cannon during the circus. The guy being shot out of the cannon in this example only gets shot out once a night but he spends a lot of time beforehand making sure the barrel has no obstructions, that the propellant is properly balanced, and so forth.
Also, as this can never be said too much, the Phowa practice is very, very dangerous and shouldn't even be CONSIDERED unless one has a teacher and even then it should be undertaken with the utmost caution.
IN THIS BOOK IT IS SPOKEN OF THE SEPHIROTH & THE PATHS, OF SPIRITS & CONJURATIONS, OF GODS, SPHERES, PLANES & MANY OTHER THINGS WHICH MAY OR MAY NOT EXIST. IT IS IMMATERIAL WHETHER THEY EXIST OR NOT. BY DOING CERTAIN THINGS CERTAIN RESULTS FOLLOW; STUDENTS ARE MOST EARNESTLY WARNED AGAINST ATTRIBUTING OBJECTIVE REALITY OR PHILOSOPHICAL VALIDITY TO ANY OF THEM.
Wagner, Eric; Wilson, Robert Anton (2004-12-01). An Insider's Guide to Robert Anton Wilson (Kindle Locations 1626-1629). New Falcon Publications. Kindle Edition., quoting from Alister Crowley