In support of the ITER disruption mitigation system (DMS), a highly flexible, triple-barrel shattered pellet injection (SPI) system was installed at ASDEX Upgrade and tested in 240 dedicated discharges in the 2022 experimental campaign. Prior to the tokamak experiments, the system was commissioned and characterised in a laboratory environment. In this paper we discuss the experience gained from 2000 pellet launches on the freezing and launching process for 4 mm and 8 mm diameter pellets made from deuterium, neon and their mixtures. Different amounts of neon inside the pellet as well as the pellet heating recipes show a significant impact on pellet quality and successful launching. Pellet recipes were developed pushing the lower boundary of successful pellet launches. Depending on pellet size and composition, velocities between 60 m/s and 750 m/s were achieved.