some cases are not worth your time, but it can be hard to predict these cases. To many pathologists renal biopsies are not worth it - the time it takes to learn how to interpret them is extreme, plus there are lots of ancillary tests, clinically correlation, sending things out for EM which is an extra cost.
Dermpaths can do more cases if they specialize. Many dermpaths do around 10-15000 cases per year, the extreme can be close to 50,000 for experienced reference-lab type pathologists. People who do stuff like breast or GU, it's going to be a lot less, closer to 1000-2000 per year. If you see a mix of everything it might be closer to 5000. In academics it will be less because you are not on service all the time.