The ensemble size, that is the number of replicas to be performed at each λ point, is the choice that needs further discussion as each added replica comes with additional computational cost (albeit no additional wall clock time is required on a supercomputer). So, one needs to find a trade-off between the computational cost and the level of precision (and consequently accuracy) desired, especially when the number of ligand pairs are large. For large-scale free energy calculations, a suggested way to employ TIES (or any other free energy method of choice) could be to decide a desired level of precision in terms of a threshold value of statistical uncertainty (σ). Thereafter, one can start with a 'floor value' of ensemble size and perform calculations for all ligand pairs, followed by a stepwise increase in the ensemble size only for those ligands for which the resultant uncertainties are above the threshold σ.