Midjourney offers a couple of ways for subscribers to earn extra Fast time. You must have an active subscription to use bonus time, and it expires 30 days after it's awarded.

Every day, the users who have ranked the most images each earn a free hour of Fast time. If you're in the top rankers for the day, you'll get a direct message from Midjourney Bot in Discord around midnight UTC. When ranking images, choose the image you prefer aesthetically, regardless of prompt adherence.

Periodically, Midjourney offers surveys. The data collected from these surveys is used for research purposes. The amount of Fast time you can earn varies. You can see open surveys and how much fast time you can earn on the Surveys page.