The bottom line is that we each have our own opinion of what constitutes a optimum number of rounds we feel safe carrying. Nobody is wrong.. If carrying a 18round mag and 4 spare bandoleers under your shirt makes you feel safe, go for it.
I have CC everything between a 5 shot 38 snub to a 12 round 9mm. Each time I have felt well armed. Once I CC a twin shot .22 derringer (a gift) which I feel was inadequate so I had a 357 at my waist.