Started playing kirby's return to dreamland again recently. Haven't beaten the extra mode yet after literally beating the main game on day 1. I didn't beat it 100% on day 1 but all the levels were completed on day 1. I didn't come back to 100% the main game until a few months later out of laziness and it wasn't until just now I gave the extra mode a shot.
I played the regular mode in co op mode so the game felt pretty easy because of that but extra mode already having increased difficulty and playing that 1 player so far it has been pretty challenging actually. I do plan to beat extra mode 100% so I can get a total completion on the game finally.