Assuming single-dosing why would anyone possibly want to leave coffee in the grinder, only to stale and require a purge before the next use. Why not have an accurate, predictable dose, when it is easy to do so? If grinder, machine, coffee, water, and barista skills are good enough, it is pretty easy to taste a difference in dose of .3g. That said, there are other ways to compensate for minor dose changes, but I prefer to use those techniques to fine tune extraction and taste, which is much easier if I hold the dose constant as I tweak other parameters. Some coffees obviously require different doses for optimal extraction, but random intershot dose variation is not the way to achieve this.