Larry Bud wrote:
....
Are you being sarcastic? You glue up with a biscuit, the glue swells
the biscuit, you sand, the glue on the biscuit dries, the biscuit
shrinks, a depression is formed where you sanded.

I know folks keep saying that, but I've never been able to observe it...

Maybe because I work slowly enough owing to other constraints that by
the time I get from initial construction to finishing things have dried
already or (more likely) the thickness of the piece is sufficient as to
make the differential exapnsion unobservable w/o more precise
measurement than I'm ever going to make on a wooden surface....