A Cafe24 inventory sync failing silently will cost you more than any bidding misconfiguration ever will.
On one account I operate at ₩50M+/month, Advantage+ Shopping kept spending heavily against a product that had been out of stock for three days. The product converted well historically, so Meta's model kept allocating budget to it — right into a dead checkout. ASC has no product set exclusion lever. There is no way to tell it "stop buying against SKU #4471 until inventory is back." Manual campaigns with dynamic product ad sets let you exclude OOS SKUs at the feed level. That one structural difference, at serious Korean D2C scale, is worth more than any auction consolidation gain ASC offers.
The other thing that doesn't get talked about enough: flash sale signal contamination. Running a 48-hour, 35% discount event inside an ASC campaign teaches the model a lower AOV baseline. Post-promotion, it undershoots ROAS targets for weeks — not because your product got worse, but because the campaign is still chasing a distorted conversion value from the sale window. In a manual structure, you pause the sale ad set cleanly. Your evergreen campaign never sees the contaminated signal. This is not a minor tuning issue at ₩4M+ in monthly flash sale spend; it compounds into a meaningful efficiency gap every cycle.
None of this means ASC is bad. On clean, single-brand accounts under ₩40M/month with stable catalogs and a creative team shipping 4+ assets per week, I've measured 30-50% efficiency improvements from letting ASC collapse overlapping ad sets into one unified auction. The "broad audience only" constraint matters a lot less than expected on accounts with 12+ months of purchase history — Meta's model outperforms hand-built Lookalikes on those accounts now. The honest answer is that ASC vs. manual is the wrong question. The right question is whether your catalog stability, promotional cadence, and signal quality actually match the conditions ASC was built for.
I wrote up the full breakdown — including the Naver + Meta attribution overlap problem and a decision table for exactly when to switch structures — over on themedilog.com.
