What is considered current best practice to test own strategies which are based on hypothesis? There are e.g. tests about how good examples shrink HypothesisWorks/hypothesis-python/tests/quality/test_shrink_quality.py. However I could not find examples so far which test the data generation functionality of strategies (in general, performance, etc.).
Hypothesis runs a series of health checks on each strategy you use, including for time taken to generate data and the proportion of generation attempts that succeed - try e.g. none().map(lambda x: time.sleep(2)).example() or integers().map(lambda x: x % 17 == 0).example() to see them in action!
In most cases you do not need to test your own strategies beyond using these healthchecks. Instead, I would check that your tests are sufficient by using a code coverage library.