The injection of CO2 into subsurface reservoirs provides a long term solution for anthropogenic emissions. A variable injection rate (such as ramping the flow rate up or down) provides flexibility to injection sites, and could influence the amount of residual trapping. Observations made in cm-scale samples showed that starting at a low flow rate established a flow pathway across the core, leading to a long term reduction in pore space utilization, as increases in flux were accommodated with little change in saturation. In this work we assess the scalability of these observations by performing experiments with variable injection rates in larger samples: 5 cm diameter and 12 cm length, compared to 2.5 cm diameter and 4.5 cm length in our previous work (Spurin et al., 2024). We observed that starting at a low flow rate did not lead to a long term reduction in pore space utilization. Instead saturation increased significantly with increased flux, leading to a higher pore space utilization than experiments where injection started with the higher flow rate. The difference in observations depending on sample size and the role of heterogeneity highlights potential uncertainties in upscaling experimental observations to field-scale applications.