Have you ever worn a pencil skirt on a day you have not had to do anything formal?

Yes, one of my more basic winter skirts is a stretch velour pencil skirt that's about mid-calf length. I'm carrying extra weight between waist and knees, and it's surprising this skirt flatters like it does. It must be fifteen years old, at least.

While it can be dressed up, I more often wear it with a sweater or tunic-style top.

Yes, wear them to work occasionally 

I don't wear pencil cut skirts. I want freedom of movement. 

Pencil as in a simple straight silouhette? No. I find them the plain vanilla of all skirt flavors. But I've worn A line, circle, Godet, panelled, gored,  flared, flounced, flowy, ruffled, puffed, pleated, vented, half circle, drindl, trumpet, mermaid, and more. A straight pencil skirt isn't really formal, it's a rather basic office look. A straight pencil skirt is actually kind of boring. 

that sounds like something people would do now that quarantine is going on haha

no, barely ever wear pencil skirts