If you have a UV5R radio you know out of the box the squelch settings are wrong. There are fixes here and there and do work in a perfect world. However the world is not perfect and for me even less so. I have a cell tower within a block and a half from me and street lights that the city say are not monitored remotely, but are monitored remotely. And then I have all manor of electronic devices around me. So this little radio will waste it's juice airing different radio bursts that I don't really want to hear. So this was my numeric fix for this crappy little radio. So far I'm riding on setting 6 at work.
You'll notice I didn't go to 100%. Yeah after 65% if you're not standing on top of the person you're not hearing them.
Addendum: I call the radio crappy but don't get me wrong. I like this little radio and all it's little brothers and sisters I have in my junk drawer. Best 20$ I ever spent. It got me into amateur radio. And if I loose it, get's damaged or it goes scuba diving in the toilet I truly don't care. 20$ and it's replaced. Just like my budget Craig Action Cam(GoPro look alike), do you want to loose 400$ or 15$ on the milsim battlefield?