How to save efficiently?

If you keep tapping the middle part, you'll see a message saying 'Halve fermentation time by watching ads'. Just do that and leave the rest alone.🤔

As the person above mentioned, if you tap the center after 1 minute from the start, you can halve the time by watching an ad. By the way, you don't need to keep tapping for the whole minute. You can't close the app until you can watch the ad, but you can close it after watching.

Thank you.