Is 8 enough?
Nobody here goes looking for trouble, but you can, for instance, be detoured into a bad neighborhood and your car break down. It happens.
8 should be enough for 1 or 2 assailants.
Three, four, five or more assailants is big trouble and calls for superior fighting skills and a handgun that can deliver overwhelming force. For me, its a snubby, a S&W 44 Mag. Only 6 shots but if the bad guys haven't quit by the time its empty, there is usually 1 or 2 New York reloads on hand.
"Of course there is a situation where a Glock 17 with several 33 round magazines wouldn't be enough." [fallingrock71]
couple = 2 mags
few = 3 mags
several = 4 or more mags
That means carrying a Glock 17 with 34 rounds on board plus 4 - 33 rd mags, for a total of 166 rounds on hand.
Can't imagine a threat that would require more than 166 rounds to stop.
Is 8 good enough? Most of the time yes. But 20 is best.
For 20 years the sea was my home, always recall the sun going down, and my trusty friend, a 1911 pistol, strapped to my side.