This topic (breast screening) is a good example due to the sheer scale. If you increase the work-up rate by even a smallish amount, you are statistically pretty much guaranteed to kill people who did not have the disease. How this balances about gain (i.e. save other lives) is not obvious. Figuring out the "right" way to do this is real work.
Also a good example because there's actually been recent push back on mammography because the risks may outweigh the rewards (especially in younger age brackets). More testing does not automatically equal better outcomes. Here's one summary from the Nordic Cochrane Center (for those that don't know Cochrane is one of the gold standard organizations for evaluating the quality of biomedical research via systematic reviews https://en.wikipedia.org/wiki/Cochrane_(organisation) ):
Extremely important, and is the most important question to ask in any screening scenario.
It's not the case the more screening is always better. There are plenty of screening regimes that you've never heard about because the trial data didn't support it.
This topic (breast screening) is a good example due to the sheer scale. If you increase the work-up rate by even a smallish amount, you are statistically pretty much guaranteed to kill people who did not have the disease. How this balances about gain (i.e. save other lives) is not obvious. Figuring out the "right" way to do this is real work.