Exactly

And there is another variation: you have something all the time, except when you need it and find out you forgot it at home only that one time.

I used to carry two pens, not one, but two (blue and black ink). They are on me even at home, and only leave my pocket when I go to sleep. Then one day I was going to meet a guy in a cafe to discuss some business. When the discussion needed some drawing and writing, I had NONE of my pens on me !!