ANSWER

Once a bug is identified there are a number of advantages to fixing it as quickly as possible.  

• Bugs lead to inaccurate status updates and estimates.  It’s difficult to estimate the full impact to the project schedule of outstanding bugs. Inevitably, as the project progresses bug fixes and the identification of new bugs seem to take up a larger and larger percentage of the developers’ time.  It’s quite common for projects to near the 85-90% completion mark only to hover around that level for some time as bugs continue to be discovered and fixed.  

• Discussing bugs is an inefficient use of time.  Tracking bugs, prioritizing when they should be fixed, and determining how much time it will take to fix them is non-productive.  The longer bugs remains unfixed the more time is spent reviewing them during each planning and status meeting.

• Unfixed bugs hide other bugs.  You can fix one bug only to discover another that wasn’t apparent until the first bug was fixed.  Even worse, the new bug that you uncover may be more severe than the original bug and now it’s being fixed much later in the development process.

• Bugs make it hard for a team to know if they are reviewing unfinished work or if a bug really exists.  Since testing occurs at all stages of development, testers and users often will be reviewing unfinished features within and application.  As they stumble across bugs they must try to assess whether it’s an actual bug or whether its just a feature that isn’t fully coded yet. 

• Unfixed bugs suggest to the team that quality isn’t important.  By allowing unfixed bugs to linger and not placing an appropriate emphasis on them, the root causes of bugs (poor specs, poor coding) persist.  This creates an environment where mediocrity becomes the status quo.

• Unfixed bugs misappropriate the time spent by testers.  Good developers should be constantly unit testing their own code.  However, when mediocre work becomes the status quo too much is left for the testers to discover.  This moves the attention of the testers away from finding the more difficult and complex bugs to finding surface level bugs that should have been fixed prior to QA.  Ultimately, this causes testing fatigue and increases the chance the testers will fail to uncover other more complex bugs.

• Fixing recent and familiar code is easier for developers.  If the developer hasn’t touched the code in several months and then needs to return to it to fix a bug, it takes more time to re-familiarize themselves with the code compared to fixing the bug shortly after the feature was coded.