I also have a tendency to have a hard time completing the sub-event decor.
Last year, I couldn’t complete the set of spring sticker decor and mahjong decor, so I spent up coins to complete the set.
Regarding playing card decor, there are 14 types of playing card decor, including jokers, and the expected number of times to complete all 14 types is 46, but even with those 46 times, the probability of completing all 14 types is only 60%.
I was able to complete the set by 50 seedlings. Therefore, I only destroyed event mushrooms during the event period.