It's been a while, but I ran into similar problems with a conference room where I had one ¾" and one ½" conduit going into a split floorbox. Obviously one would be used for power, the other for a variety of video/audio options and controls:

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Last year I added in an "eyeball camera" (bottom photo), managing to sqweak one last cable into the bundle. Zipcord was used to extend the camera's power brick to a closet about 25' away. The mount was custom-honed from a solid piece of aluminum.

So to answer to what could you possibly need that would fill a conduit? becomes obvious if your customer happens to be an engineer and bit of a showman.

"Press play and record at the same time" -- Tim Alberstein