It been my long held opinion that ...."Only you" can assess your needs!
Where do you live, what's your job, where do you go, how do you dress , what is your skill level........would the possible risks you face require 5,6,7,12,15,17 rounds in a handgun and one or two extra magazines..... or should you just get a rifle or shotgun???????
5 plus a reload is just about the minimal load..... but it doesn't mean it's bad or wrong......if it works for you. Better a 638 with you than a 18 shot 9mm left at home.
For years (1980s) I carried a Walther PPK .380 6+1 and a spare mag when wearing a suit...... a 3" K frame 6 shot .357 (loaded with +P.38s) with a speedloader on the weekends.
What do they mean when they advise a "9mm with an extra magazine"?????
My EDC (since about 1990) 9mm is a S&W 3913 with 7+1 plus a 8 round spare mag. For me I'm good to go in my Burb of the Burgh....... if the world changes... or the SHTF then maybe a 3913 isn't the right gun.......
But I have a PC6906 9mm which is 12+1 with a spare 15rd mag.
or a Beretta 92 Centurion .... mine is 17+1 with spare 18 or 20 round mag.