Actual answer for this;
DPI precision is a "hold key to stay at X dpi" setting, so if you'd bind a key to precision and hold down that button, it'll stay at the precision DPI until you let go.
It's useful for when you're aiming at distant targets but I personally prefer to just switch DPI as I already have to hold the scope button.
Reviving this months old thread so someone else looking this up will get some actual info, I personally had trouble finding the answer until I tested it for myself.