I once worked for a company with very old software that was used all over the country. There was no Scrum, no plannings, no shitty managers. We were free and productive.
Every bug was an opportunity to fix, refactor, and improve the code. That's where I had the most fun until it was bought by an investment fund company which fired most people. The original company was making millions by being a niche on the market, but the new owners decided that it was not enough for some reason. Fun times.