CLOCK and neoplasm: Alexandrov et al. (2015) have identified tumour type specific differences in the clock-like nature of signatures 1 and 5. Further, Rubanova et al. (2020) observed changes in the activity of these signatures over time, suggesting that their mutation rate may not be entirely constant. This potential variation in the clock-like nature and consistency of these mutational signatures may in part underlie some of the unwanted behaviours that we observe with AmplificationTimeR, such as timing estimates >1.