It’s hilarious this is still a thing - and people think they are being “innovative” in trying it (and that card companies aren’t aware buyers would try it.
In the late 80s I paid off clerks at every retail store to give me a chance to check their rack pack cases on arrival before opening. Would come in and have my master list - could tell you exactly where the Ripken FF, Jefferies and Griffey RC as well as any other card of interest was. Of course certain product we just bought them out of still sealed (mainly Fleer) as I could pay $1 and sell it for $1.75-2 easy.
The 2nd or 3rd year of Upper Deck Baseketball has the first real “chase” card I could think of - was a Jordan insert and it sold for like $50 from memory. If I remember correctly it was a Toys ‘R US exclusive. The thing was cards came 15 to a pack - but there would be 16 if the insert was present. Anyway - my best friend worked Early AM inventory at Toys R Us and got me on as seasonal help - the 2 of us with micrometers searched every pack our stores got and likely got every one of those inserts.
So many tricks in this hobby back in the day - it’s like card restoration that they sell now for vintage stuff. I couldn’t tell you the number of corners I shaved and pen ink I removed from classic cards to make them more attractive in the 80s/90s. Exacto knives, magnifying lamp and jewelers loop were my tools of the trade.