I don't doubt what you are saying at all if your ground is mild. It doesn't really affect performance in disc mode, unlike with other detectors. I know that on dry sand on my beaches, GB balances to zero. However, in mineralized ground (basically where I do 90% of my detecting), if you do not GB then ground noise overwhelms horseshoe mode and makes it unusable. Even in mineralized ground, it is not something you would really notice if you never use no disc/horseshoe mode - but I use it often (to find iron concentrations indicative of old building sites and to reduce clipping of non-ferrous targets that have a ferrous signal component due to depth or corrosion).
Doing an Auto GB/ground grab is just part of my normal Equinox startup routine just as noise cancelling, regardless of the site. Like I said, there is no down side to doing an auto GB, even if the GB returns a zero. It only takes a few seconds.