Comment by loonster

The cost of the part doesn't matter. The cost of my time does.

For common components, I need a parametric part so that I can instantly change the length, size or type. If my M12 becomes an M16, I want all the taps and C'Bores to adjust without any further input from myself.

For more expensive parts, it's nice to have a homegrown parametric part to minimize potential missorders.