Mattg, you're right in the way you calculate the effective coin-supply ratio, but if you reverse it and calculate the effective supply per coin ratio, you'll see that the idea factories are more punishing and cost a lot more coins for the supply you earn. This is intentional due to the fact your overall output is higher. You slightly cut into your profitability, but as you progress into higher levels, your profits per supply increase from higher level businesses.

This will be addressed in the big update I'm working on, where the best value overall will come from short term contracts (1/3/5/10/15 minutes) which will effectively eat up a lot of player energy, but will keep the game sessions fun and engaging. We'll also offer long timers (8/12/16/18/24+ hours) that will have a much weaker yield for their time. My goal is to encourage more consistent daily play (3-5 times a day), as opposed to long term once daily play.