I personally, on multiple occasions, have opened a booster to play Limited only to realize I was accidentally opening a Set Booster
The Future When the Jaws: Terror of Amity Island Secret Lair drop was announced, Wizards revealed theyd be handling it differently from usual
However, the creation of decayed creatures is tacked on to the effect of other cards, so even though the mechanic itself is an inherent downside, the card creating those creatures can still be quite good
Stacking up several Spidops ex may as well be a winning strategy even though its a Stage 1 card but with a very low attack cost
But heres the thing, you dont have to own the original to have access to the effect
As for when to buy cards, I have two clear rules here too: First is that you get personal copies whenever you want