In the engine, the pak format supports file names up to 56 characters (55 + trailing null?)
Doesn't care about length of any of the file name components, etc.
Think about all the releases with skyboxes and how some of releases like Zendar have the skybox in a pak file!
https://www.quaddicted.com/reviews/zendar1d.html <--- Quaddicted shows just pak0.pak and pak1.pak --- pak0.pak containers a skybox named nightzen_up.tga , nightzen_bk.rga, etc. etc.