In a game I played just now:
I play several King's Courts in a row on Schemes, a Laboratory, a couple Bazaars, and a couple Woodcutters, and buy up almost all the duchies, because my opponent has a massive province lead and as long as I get another turn, my Schemed Kings Courts will allow me to get another massive turn to end it next turn.
So with 9 cards I may put back due to King's Courted Schemes, I put back: King's Court, King's Court, King's Court, King's Court, King's Court, Laboratory, Scheme, Scheme, Woodcutter.
I get very excited because my opponent must have had a lot of green on the top of his deck: he has two kings courts and schemes, and they're not able to draw most of his engine and he just buys a single gold. I'll be able to pull off the victory from behind and buy up all the remaining provinces and duchies with my next turn for sure.
So I excitedly start my mega turn. I play a King's Court, on a King's Court, on a King's Court, on a King's Court, on a King's Court
... on nothing because I have no remaining action cards, times nine.