Many bugs that have already been fixed will reappear in later patches. It feels like it to me that code changes are overwritten again by importing old branches or the effects of fixes are nullified again. With some bugs it also seems to me as if some developer has changed a value for the solution of his problem and has thus broken the whole rest of the system. Do you have something like a testing framework that checks the source code for new bugs? Is there test-driven development? Do you have uniform coding standards and is compliance with them monitored? To what extent is the build of new revisions automated and secured by checking routines? MAIN QUESTION: What is being done to improve the quality of software development?