Fun fact: you dont need to be AFK, there is MUCH faster way. The thing is... When the limit scene triggers, for some reason you still can press buttons during it. So, when you encounter the first fairy on fire puzzle that increases your breast growth, you can just spam interaction button and it will skip the first limit scene dialog but will start talking to fairy before the next one starts, and so in cycle.
But sadly, the breasts wont grow visually, just the number.