A single-blade folder is my most most fundamental survival tool. If there room for only one tool to carry, it would a single-blade folder. I might be walking/jogging while wearing workout shorts. I would not be able to carry a multi-tool because it's too heavy, but at least I can have a single-blade folder in my right front pocket.

When I get dressed, it's like clockwork. My single-blade folder goes on me every time for any kind of attire, including suits, jeans, shorts, etc.