Background: Workforce reform is central to improving aged care quality. In 2023, Australia introduced mandatory care minute targets for long-term care facilities (LTCFs), to lift minimum staffing levels. However, it remains unclear whether this reform has reduced variation in delivered care, and whether remaining differences reflect resident needs, geography, or organisational factors. This study examined national trends and sources of variation in total and registered nurse care minutes across Australian LTCFs. Methods: We conducted a retrospective cohort study using national Star Ratings data from April–June 2023 to January–March 2025, including 2,578 LTCFs. Outcomes were total and registered nurse care minutes per resident-day. Multilevel linear mixed-effects models partitioned variation across LTCF-quarter, LTCF, and regional levels, with sequential adjustment for facility characteristics, regional factors, and resident care needs. Results: Average staffing increased by 25 total care minutes and 7 registered nurse minutes per resident-day, indicating reform uptake. However, variation persisted: LTCFs at the 75th percentile delivered 23 more care minutes per resident-day than those at the 25th percentile. Most variation was between LTCFs (62–74%), while regional variation was minimal (approximately 1–3%). Resident care needs explained 11% of variation in total care minutes and 2.4% in registered nurse minutes. Facility ownership explained more variation than resident case mix, with government-run LTCFs consistently delivering higher staffing. Conclusion: Mandatory staffing reform increased average care delivery but did not eliminate inequities. Achieving the Ageing Revolution will require policy levers that address organisational and funding drivers of unequal care provision.