I'm making a Quake map, and on testing the ilumination on floor looks very rare, I'll provide few screenshoots to show you what I mean:

https://i.imgur.com/MrXmFiL.png
https://i.imgur.com/y3NPEQ5.png
https://i.imgur.com/dY0EEvw.png

An idea why happen that and how fix it. Im using Jackhammer. I'll give jackhammer map file to see if there is something wrong on map.

https://drive.google.com/file/d/1WbTvKvV5E_QmXzRLDuPUrEG0FgKtKHWQ/view?usp=sharing 

Those pillars are floating 1 or 2 units off the ground. I would make them touch the ground (or even intersect with the ground).

If you are using current tools then you can make the pillars into a brush entity func_detail_wall, or func_detail, give them "_shadow" "1" as keys/values (I would also give them "_phong" "1" for a smoother shading).

You can also add dirt mapping for baked ambient occlusion - run:
light.exe -extra -dirt

The tools I would use are here:

https://ericwa.github.io/ericw-tools/