Conflicting OP Durations - 20 minutes once or 3 to 4 minutes thrice as suggested by Andreas Moritz ?

I have been doing oil pulling for almost half a year. I do it on empty stomach every morning for 20 minutes. But today when I read Andreas Moritz ’s book Timeless Secrets of Health and Rejuvenation (P. 141), I found that Andreas suggested to oil pull for 3 to 4 minutes and repeat it for two more times to avoid any released toxins to be reabsorbed.

Should I follow Andreas’s instructions of OP for 3 to 4 minutes thrice or keep on what I have been doing i.e. OP for 20 minutes once?