Most of the time, 1 safety bowl is enough, but it is not uncommon to smoke up to 3 or even sometimes 4 safety bowls to ensure that you are indeed high enough.
The safety bowl is not to be confused with the bedtime bowl, however the safety bowl can lead directly to sleep.
"Damn, I didn't smoke enough... I should've packed a safety bowl."
"I am so retarded. Those last 2 safety bowls were completely unnecessary, but oh so sweet."