Context : We present a large homogeneous set of stellar parameters and abundances across a broad range of metallicities , involving 13 classical dwarf spheroidal ( dSph ) and ultra-faint dSph ( UFD ) galaxies . In total this study includes 380 stars in Fornax , Sagittarius , Sculptor , Sextans , Carina , Ursa Minor , Draco , Reticulum II , Bootes I , Ursa Major II , Leo I , Segue I , and Triangulum II . This sample represents the largest , homogeneous , high-resolution study of dSph galaxies to date . Aims : With our homogeneously derived catalog , we are able to search for similar and deviating trends across different galaxies . We investigate the mass dependence of the individual systems on the production of \alpha -elements , but also try to shed light on the long-standing puzzle of the dominant production site of r-process elements . Methods : We use data from the Keck observatory archive and the ESO reduced archive to reanalyze stars from these 13 classical dSph and UFD galaxies . We automatize the step of obtaining stellar parameters , but run a full spectrum synthesis ( 1D , local thermal equilibrium ) to derive all abundances except for iron ( applying non-local thermodynamic equilibrium corrections where possible ) . Results : The homogenized set of abundances yielded the unique possibility to derive a relation between the onset of type Ia supernovae and the stellar mass of the galaxy . Furthermore , we derived a formula to estimate the evolution of \alpha -elements . This reveals a universal relation of these systems across a large range in mass . Finally , we showed that between stellar masses of 2.1 \cdot 10 ^ { 7 } M _ { \odot } and 2.9 \cdot 10 ^ { 5 } M _ { \odot } there is no dependence of the production of heavy r-process elements on the stellar mass of the galaxy . Conclusions : Placing all abundances consistently on the same scale is crucial to answer questions about the chemical history of galaxies . By homogeneously analysing Ba and Eu in the 13 systems , we have traced the onset of the s-process and found it to increase with metallicity as a function of the galaxy ’ s stellar mass . Moreover , the r-process material correlates with the \alpha -elements indicating some co-production of these , which in turn would point towards rare core-collapse supernovae rather than binary neutron star mergers as host for the r-process at low [ Fe/H ] in the investigated dSph systems .