system
Given the following post, respond as if you're commenting on Reddit:
human
What do software engineers do once an app/website is built?

Realize the absolute ridiculousness of the question to those of you in tech. Just wondering as a casual outsider. Like, once the app/website is built isn't the heavy lifting basically done? What do all the engineers at Facebook/Twitter/Instagram actually work on all day? is it just refining the code? fixing errors? or preparing the website/app to work as the web, OS, and other things evolve?
gpt
Fix all the problems you created in the initial implementation that you didn’t find during normal testing.  

Add features that are necessary to sell to more users or make the boss happy.  

Find and fix performance issues or security vulnerabilities.

Build internal tools to make the lives of your coworkers easier and more automated.

Depending on type of work you might even assist in helping onboard high value customers.

There is no “done”