Whereas, the number of compounds that could be synthesized for the 'bespoke' library was consistently under-predicted. This highlights that only considering the number of compounds for which routes can be predicted does not afford enough granularity for the assessment of synthetic routes, and CASP tools. Furthermore, the reasons for a 'failed' synthesis are not always known and can be dependent on the nature of the project, the skill of the chemist, and the conditions used, to name a few factors influencing the outcome of a synthesis. These factors cannot always be quantified or considered qualitatively, thus both the predictions and 'true' experimental results have an associated degree of uncertainty which proves difficult to measure.