Everyday.
I also keep a multi-tool of some description - small, pocket sized for work, hip version for after work (except when flying, then it's iny checked bag). A handful of tools which are useful everyday for opening boxes, removing splinters, fixing things - all sorts of uses, that if I was without these implements, I would not feel useful or independent; these characteristics are important to me.
A pocket knife and a multi tool give me a sense of security and resourcefulness, in that I'm able to make and fix things that have others stumped (I'm in the city these days, but didn't start out that way).
So, Baden-Powell instructed, 'always be prepared,' and long ago my father taught me to be resourceful; with my pocket knife and multi-tool, I am.