I will add that you can do 100x and 200x with OOPArts. However you'd need to wait some time for the game to save. You can check on the top left corner if the game's autosaving or not.
I wouldn't mind ads if it's for a choosable item multiplier. Both r nice options.
Some content sometimes needs a lot of items to complete, like another dungeon episode drops, and light/shadow off the top of my head.. Not sure why you would stop at 200x though 🥲