Even if you work on a commercial project, where there is a reasonably stable core team, people just committing stuff, even if it's in itself pretty good stuff,

Even if you work on a commercial project, where there is a reasonably stable core team, people just committing stuff, even if it's in itself pretty good stuff, won't result in good overall code quality. You need to have a systematic process, including a detailed coding standard, requirements about test and documentation coverage for submitted code, precise guidelines for contributing, rules of code review, and you need people who understand the whole project, review pretty much all of the code changes, have an overall development schedule in mind including refactorings and technical improvements, and all the time putting work into maintaining overall integrity of the project: http://c2.com/cgi/wiki?ConceptualIntegrity http://c2.com/cgi/wiki?ConceptualIntegrity This is pretty much a must for any project where there is more than one person working, and the more people contributing or the more mission-critical the project the more of this kind of high-level coordination is required. Some open source projects with strong leadership do get to this kind of integrity, but most don't. It's easier when there is a relatively small team of very dedicated individuals, but some large projects have succeeded to some extent in building a real development culture in an open source setting, like Linux.