This is not the only essential piece of gear that you need to carry along for productions. When doing video or audio (or both), our crew always carries at least one 100ft. XLR cable. This has saved us in many scenarios.
Live sound setting. We bring a snake with 4 returns and all of a sudden a 5th return is needed. You can “home run” your 100ft microphone cable along side your snake. Problem solved.
Video setting: Recording a corporate round table session. Simple setup. Once camera in the back of the room with a wide shot covering the event. All microphones are routed to a mixer that is about 70ft. away. On the mixer, your L main output is going to the main speakers. Take the R main output and run your 100ft XLR all the way to the camera input. This saves us from having to sync audio in the post edit. A second audio track is recorded using a zoom h5 just for backup.
The simple truth of production is that you will have moments come up where you have to improvise. Having this piece of gear will solve problems on set.