I work at an agency that used to build websites and small apps, but the past years we've been shifting towards larger web apps and products, both for ourselves and for clients.
Small projects are easy to manage. GitHub issues or Basecamp todos are more than enough to keep going. Adding a feature or refactoring a small project is also easy, because there aren't too many moving parts to take consider.
On the other hand, Large and especially long-living projects are constant moving targets. It's harder to estimate things and technical debt can become a real issue. A linear, chronological task list won't do it anymore, we need to start prioritizing.
I want to share four systems that have helped me, and sometimes my team, prioritize work on large projects.