you should carry as many blades as YOU feel comfortable with.

i only carry a Wenger exsecutive and a Vic Swisscard most of the time, so i won't get in to trouble at school or other public places. Wenn i just go somewhere, where i can carry blades i will add mine Swisstool X or/and a opinel #7. I don't need a one-hand openable knife for most jobs, so i don't carry one.