It is impossible to cover all possible events and testcases. Nevertheless, it is possible to cover all useful testcases. Our experience shows that it is useful to cover about 80% of all testcases.
We found a direct correlation between developer team size and the complexity of an application. Therefore you need more testcases if you have a more complex application. We estimate about 25 testcases per developer.
Depending on the experience of the tester and the complexity of the testcases the time varies. A good starting point for an average tester is about 2 hours per test.
The global average for outsourced QA Freelancer is about 65€/hour. But bear in mind, that freelancer need some extra coaching
This varies on your development setup. 2 sprint relases a month is a good starting point. With every release your application changes. Then it is essential to promptly update your tests otherwise they start to fail or get flaky. Update your tests quickly otherwise bugs might sneak into your application undetected.
Again, the time depends on the experience of the tester and the complexity of the testcases. A good starting point for an average tester is about 2 hours per test.
This number depends strongly on the setup of you deployment process. Integrated pipelines conduct more daily test suite runs than non integrated ones.
This becomes more and more important as your developer teams grows. In order to prevent them blocking each other, parallelization is the key. With its increasing importance, parallelization got more expensive in recent times. Referencing on the biggest cross-browser testing platforms, we calculate with €114 per parallel test run per month.