We assessed the effectiveness of a treatment strategy based on hematoma characteristics and volume. From September 2022 to December 2023 (the Study period), a two-center retrospective observational study of initial chronic subdural hematoma (CSDH) was performed. The baseline period was from January 2018 to December 2019. Patients were classified into the high and low retreatment rate groups (Groups H and L, respectively). During the Study period, Group H was treated with drainage and middle meningeal artery embolization (MMAE), while Group L was treated with drainage or MMAE alone. During the Baseline period, all the patients were treated with drainage alone. The primary and secondary endpoints were group retreatment rates and severe procedure-related complications requiring surgical intervention and permanent sequelae, respectively. Fifty-two patients were included during the Study period (31 in Group H and 21 in Group L) and 53 during the Baseline period (32 in Group H and 21 in Group L). Three (5.8%) and nine (17.0%) patients required retreatment in the Study and Baseline periods, respectively (p = 0.12). One (3.2%) and nine (28.1%) patients in Group H required retreatment during the Study and Baseline periods, respectively (p = 0.01). Similarly, two patients (9.5%) and no patient in Group L required retreatment during the Study and Baseline periods, respectively (p = 0.49). No severe complications were reported throughout. CSDH treatment strategies that consider to hematoma volume and characteristics have the potential to identify and reduce treatment rates in cases with high retreatment rates.