If you are treating men for low testosterone, you will run into the side effect of erythrocytosis. Expect it.
Testosterone stimulates the production of red blood cells, which ultimately leads to an increase in the hematocrit and hemoglobin. If the hematocrit goes above 54%, then the patient will need to donate blood. This can become a hassle for the patient and often times they will be non-compliant with phlebotomy.
A way to prevent this side effect is to divide the weekly injection into 2-4 doses or switch the patient to a topical product. One of the issues with pellets is that if the hematocrit continues to spike, then the pellets need to be removed, which can get messy. This is another reason I do not like pellets.
Splitting the dose and administering it more frequently lowers the erythrocytosis. Large single doses of testosterone are what cause the erythrocytosis, therefore smaller doses will prevent this but be aware, some men will continue to have elevations in their hematocrit and will need to continue donating blood every 2 months.