Some goggles provide an auto-scan function, it scans for any strong signals from nearby video transmission in the 5.8ghz frequency and finds the nearest "best" channel to tune into.
While you are flying alone or in a training setup, when you get interference you can take your own sweet time pressing the auto-scan and get a clear channel again.
But during a competition, there are many participants and everyone need to follow a tight schedule to complete all the mission runs. Therefore it is critical for each participant to lock into their own designated band + channel manually.
This ensures you are at the designated band + channel exactly.
Below shows why it is important to set it manually:
Requirement: The drone/whoop/quad has already been set to the required Band-R + Channel 1. (How to set is not covered in this article)
Participant required to set goggles to Band-R + Channel 1 (Highlighted green cell). For info, this channel frequency is 5658.
Currently his/her goggle is at Band-A + Channel 2, if using the auto-scan button, it will traverse from its current position sequentially to Band-A + Channel 8, then goes to Band-B cant find, proceed to Band-E and stops at Band-E + Channel 3 (5665). This is a very close frequency therefore it might find it has a good enough signal to show. While flying alone it is fine, but when there are a few flyers around, this might not be good enough as another near frequency will interfere with it.
Therefore to reduce the chances of having interference we set our goggles to match the drone/whoop/quad we flying to the exact channel instead.
Disclaimer: Not all goggles auto-scan function traverse this way, this is just a depiction of how auto-scan can work and why it is better to set it manually. Different modules use their own algorithms.
Each goggle have their own way of changing the band and channel, below list contains some common ones.