Depends how you use it. I single dose my WBC & sweep the chute/outer burr area so retention is .1-.2g. If you run it with a hopper full of beans & sweep the chute you'd be looking at close to 6g that would need to be purged.

I have the K10 Fresh instead of the WBC and it likely retains around 7g (I did some tests that showed 4g retention but those may have been flawed). I still love the grinder despite the retention, but in retrospect maybe the WBC model would have made more sense.