The difference between the raw distribution and that of the models, corresponds to compounds that could not be predicted. The subsets correspond to a) common (occurring in greater than 100 K substances) b) present in drugs c) present in nature d) rare (occurring in under 1 K substances). The 'Ring Breaker' and standard models were compared for each subset and each training set, Reaxys and USPTO. Only a one-step retrosynthesis was predicted for each ZINC subset. The 'Ring Breaker' trained on Reaxys (green) consistently outperformed all other models, and the 'Ring Breaker' far outperformed the standard model regardless of the training dataset. 'Ring Breaker' exhibits the best performance for ring systems between 5 and 20 heavy atoms in size, and the predictions follow the raw distribution with a slight divergence as not all ring systems can be predicted.