As a tester, finding bugs can be satisfying, combining the sense of discovery with the feeling of helping your teammates. The more often tests are performed on the same feature, however, the less likely those tests are to find new bugs. Are you concentrating your tests on the parts of your app where bugs are more likely to hide?
Consider the concept of Defect Clusters. Over the history of an app, bugs may concentrate in certain areas. Testing areas known to contain bugs will probably have a greater probability of discovering new bugs. Even if no new bugs are discovered, knowing that error-prone features of an app work as expected provides more assurance about the reliability of an app than testing a steady, reliable feature.
Undiscovered bugs and defects are likely to cluster in:
The newest features of an app
Recently or frequently edited code
Complex flows and logic
APIs and integrations with data sources
User input and boundary values
Keep in mind that bugs are also a moving target! As defects are identified and fixed, the Pesticide Paradox suggests that testing the same areas of the application over and over will reveal fewer and fewer bugs. As sections of your app become stable and reliable, the defect clusters of your app may gradually shift.
So while cranking out stories and racing to meet your sprint commitments, don't forget to take a few steps back to look at the big picture. Concentrating testing efforts on defect clusters and tracking where those clusters drift over time will help your team find more bugs faster.
For those who want to dive deeper into focusing tests on defect clusters and how to automate this process, check out companies like Launchable and the concept of Test Impact Analysis.
Happy Testing!