12 projects a year, but what happens to the old ones?

Hello Indiehackers,
I am very new in this community, but I feel like I already learned a lot. I recently launcher my first MicroSaaS project. It has no users yet, but even the progress of creating a full product myself tought me a lot.

In the community it seems to be a common approach to build one project every month. My question is: what do you do with all the old project. Should they be so robust and automated, that they don't need any work anymore?

At the moment I'm still trying to improve my first project and work on marketing and it feels like when I would start the next project instead of working on the current one, the current will just be abandoned.

Also I don't feel the creativity flowing to find a problem to solve every month or so. But that's another topic.