Thanks for the reminder. I am a fan of the F117 and remember reading it is not immune or perfect.
The F117 was an aircraft designed with the analytical tools available at the time, hence the “faceted” look.
There are three characteristics of steal the in decreasing importance: size (bigger is bigger), shape (plan form alignment, apertures, corner reflectors), and treatments (coatings, materials, blade seals for doors, etc)
Every stealth platform implements these basic elements. We couldn’t easily calculate the radar cross section of curved surfaces when the F117 was designed, but we could calculate easily the RCS of flat surfaces. That us why the F117 looks as it does. The flat surfaces “face” the same (limited) directions so you control the signature reflections. If a radar you don’t know about is in an unfavorable place, you are toast.