It'd be great if there was a way to see average coins per second for every stage you enter, such that Average Coins per second= ((Average Monster Health / Damage per second) + Spawn time between monsters)) / (Average Coins per Monster), so that you can compare which stage is the best to go AFK on to earn the most money for your time.
Got a rare glitch where the last enemy is invincible, went ahead and earned a 2100 hit combo, got bored, went back to the menu screen, and got nothing for it :(