Sometimes, running longer simulations on the T4 lysozyme/toluene system resulted in toluene switching to the symmetry-equivalent binding mode (Figure ). When this occurs, the ligand ends up being outside the pre-specified darts we defined in this test, and thus MolDarting moves cannot be attempted. We could have instead included all four ligand binding modes (two symmetry-equivalent pairs) as darts, but we elected not to here as we wanted to focus on non-redundant sampling. This issue highlights a key point: while MolDarting can be used to accelerate sampling, it is only effective when the system is within the selected darts; when outside the darts, we are effectively running plain MD. Thus, to maximize the applicability of MolDarting moves, care should be taken when defining the regions used for MolDarting. Essentially, MolDarting attempts to trade bias for efficiency. More random procedures, like our initial translational moves in BLUES, allow enhanced exploration of binding mode transitions regardless of what pose the ligand is in, but do so rather inefficiently since so many proposed moves are to unfavorable binding modes. MolDarting requires more advance input or bias -selection of a set of potential binding modes to focus sampling on -and thus is able to ensure that proposed moves focus near those binding modes, potentially enhancing efficiency, but when the simulation strays from pre-defined binding modes, no enhanced sampling is possible.