Half-baked seems like a strong word. What's really wrong with the cleaning? If the casts turn out fine, it might not be a big deal. We often mess with stuff that works. Only worry if you see real issues.
What if the cleaning being half-baked lets tiny problems hide until it's too late? Even if the cast looks okay now, those hidden flaws could make it fail when you least expect it (kind of like a crack in a foundation that grows slowly). Waiting for a clear sign of trouble means you might already have a big mess on your hands. I've seen stuff like this where skipping small steps leads to costly fixes down the road. It's not about messing with what works, it's about avoiding risks that build up silently. To me, that's a bigger deal than just hoping for the best.
The cleaning step is maybe 30 seconds between casts. If the metal is hot enough, a lot of that residue just burns off anyway. I've never seen a flaw you could trace back to a slightly dirty ladle, only to bad metal prep or a cold pour.