Similar for me with an Oculus Quest. Maybe if I left the adjustment at one or the other extreme for an extended session, I'd notice something, but for my usual 30 minutes or so, I haven't seen any difference between settings.
I've found it affects how sharp lines look for me on Quest. I like to find a vertical line somewhere and dial in until it looks decently sharp.
Try sideloading QuestIPD [0]. It shows a test pattern that's supposed to help set the slider properly, and it shows you the exact setting value you're using.